HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Widmann, C. Articles by Johnson, G. L. Search for Related Content PubMed PubMed Citation Articles by Widmann, C. Articles by Johnson, G. L. Social Bookmarking                      What's this?

J Biol Chem, Vol. 273, Issue 12, 7141-7147, March 20, 1998

Caspase-dependent Cleavage of Signaling Proteins during Apoptosis
A TURN-OFF MECHANISM FOR ANTI-APOPTOTIC SIGNALS^*

Christian Widmann^§¶, Spencer Gibson^§, and Gary L. Johnson^§**

From the  Program in Molecular Signal Transduction, ^§ Division of Basic Sciences, National Jewish Medical and Research Center, Denver, Colorado 80206 and the ^** Department of Pharmacology, University of Colorado Medical School, Denver, Colorado 80262

	ABSTRACT

Top Abstract Introduction Procedures Results Discussion References

Caspases are activated during apoptosis and cleave specific proteins, resulting in the irreversible commitment to cell death. The signal transduction proteins MEKK1, p21-activated kinase 2, and focal adhesion kinase are caspase substrates that contribute to the cell death response when cleaved. Thirty additional signaling proteins were screened for their ability to be cleaved during apoptosis. Twenty-two of these proteins were not affected in Jurkat cells stimulated to undergo apoptosis by Fas ligation, exposure to ultraviolet-C or incubation with etoposide. Ras GTPase-activating protein was found to be a caspase substrate whose cleavage followed the same time course as that for activation of caspase activity and the cleavage of MEKK1 and focal adhesion kinase. Four additional proteins, Cbl, Cbl-b, Raf-1, and Akt-1, were cleaved later in the apoptotic response. These signaling proteins were similarly cleaved in U937 cells undergoing apoptosis. Cleavage of the proteins was blocked by caspase inhibitors in Jurkat cells or in U937 cells expressing Bclx_L, demonstrating that the cleavage was dependent on caspase activation. Cleavage of Raf-1 and Akt correlated with the loss of extracellular signal-regulated kinase and Akt activities in apoptotic cells. Neither c-Jun N-terminal kinase nor p38 mitogen-activated protein kinase was cleaved in cells undergoing apoptosis, and the activation of the c-Jun N-terminal kinase and p38 mitogen-activated protein kinase pathways was not compromised in apoptotic cells. These results indicate that caspase-dependent cleavage of specific proteins induces the turn off of survival pathways, such as the extracellular signal-regulated kinase and phosphatidylinositol-3 kinase/Akt pathways, that could otherwise interfere with the apoptotic response.

	INTRODUCTION

Top Abstract Introduction Procedures Results Discussion References

Apoptosis is regulated by a series of biochemical events that commit a cell to death. A common feature of cells undergoing apoptosis is the activation of caspases, a family of aspartic acid-directed proteases (1). Caspase substrates are rapidly being identified, but the general assumption is that caspases recognize a limited set of cellular proteins (2). Caspase-mediated proteolysis of specific proteins results in an irreversible commitment of cells to undergo apoptosis characterized by cytoplasmic shrinkage, membrane blebbing, nuclear condensation, and DNA fragmentation.

Caspase-dependent cleavage can inactivate protein substrates. Examples include poly(ADP-ribose) polymerase, lamin, and focal adhesion kinase. Cleavage of poly(ADP-ribose) polymerase abolishes its DNA repair ability in cells undergoing apoptosis, nuclear lamin degradation contributes to nuclear condensation, and cleavage of focal adhesion kinase impairs the ability of cells to maintain matrix adherence (2). In contrast, there are examples, besides the caspases themselves (3), where cleavage actually activates the substrate; examples of such substrates include MEKK1,¹ p21-activated kinase, protein kinase C, and gelsolin. When cleaved, each of these proteins contributes to the apoptotic response (4-9).

Signal transduction pathways involving the mitogen-activated protein kinases (MAPKs) including the ERKs, JNKs, and p38/HOG1 kinase, have been shown to differentially contribute to pro- and anti-apoptotic pathways (10). In addition, the phosphatidylinositol 3-phosphate-regulated protein kinase Akt has been shown to have significant anti-apoptotic signaling properties (11). This is, at least in part, mediated by the ability of Akt to phosphorylate and inactivate BAD, a pro-apoptotic member of the Bcl family (12, 13).

In this study, we have surveyed a large set of proteins that are involved in pathways regulating cell growth, cell survival, or cell death, including members of the MAPK network. Among 30 signaling proteins tested, we have identified five new protease substrates, RasGAP, Raf1, Akt-1, Cbl, and Cbl-b, that were found to be cleaved in a caspase-dependent manner during the apoptotic response induced by Fas activation, ultraviolet-C (UV-C) irradiation, and etoposide. Cleavage of Raf-1 and Akt-1 inhibited their kinase activity. This could explain why the anti-apoptotic ERK and Akt pathways are inhibited during the progression of apoptosis.

	EXPERIMENTAL PROCEDURES

Top Abstract Introduction Procedures Results Discussion References

Cells-- Jurkat and U937 cells were cultured in RPMI 1640 (Life Technologies, Inc.; catalog number 31800-022), supplemented with 100 units/ml penicillin/streptomycin (Gemini Bio-Products) and containing 10% fetal calf serum (Summit Biotechnology) (RPMI-c).

Fas Stimulation-- Jurkat cells were incubated with 1 µg/ml anti-Fas IgM antibodies (Upstate Biotechnology, Inc.; catalog number 05-201) in phosphate-buffered saline for 20-30 min on ice. The cells were then washed twice with phosphate-buffered saline, resuspended in RPMI-c, and incubated for the indicated periods of time at 37 °C, 5% CO₂. When caspase inhibitors were used, they were incubated with Jurkat cells both during the incubation with anti-Fas antibodies and during the incubation at 37 °C.

In Vitro Kinase Assays-- The cells were solubilized in TX-100 lysis buffer (70 mM -glycerophosphate, 1 mM EGTA, 100 µM Na₃VO₄, 1 mM dithiothreitol, 2 mM MgCl₂, 0.5% Triton X-100, 20 µg/ml aprotinin). Cellular debris was removed by centrifugation at 8000 × g for 5 min. Protein concentration was determined by a Bradford assay using bovine serum albumin as a standard.

c-Jun Kinase-- c-Jun kinase (JNK) activity was measured using a solid phase kinase assay in which glutathione S-transferase-c-Jun-(1-79) (GST-Jun) bound to glutathione-Sepharose 4B beads was used to affinity-purify JNK from cell lysates as described (14, 15). Quantitation of the phosphorylation of GST-Jun was performed with a PhosphorImager (Molecular Dynamics).

ERK-- ERK2 was incubated with 2 µg/ml of an anti-ERK2 (C-14) antibody (Santa Cruz Biotechnology, Inc.) for 1 h at 4 °C with agitation, followed by the addition of 15 µl of a 1:1 slurry of protein A-Sepharose beads (Sigma; catalog number P-3391) and a further 20-min incubation at 4 °C. The beads were washed twice with 1 ml of lysis buffer and twice with 1 ml of lysis buffer without Triton X-100. Thirty-five µl of the last wash was left in the tube and mixed with 20 µl of ERK reaction mix (50 mM -glycerophosphate, 100 µM Na₃VO₄, 20 mM MgCl₂, 200 µM ATP, 0.5 µCi/µl [-³²P]ATP, 400 µM epidermal growth factor receptor peptide 662-681, 100 µg/µl IP-20, 2 mM EGTA), incubated for 20 min at 20 °C. The reaction was stopped with 10 µl of 25% trichloroacetic acid and spotted on P81 Whatman paper. The samples were washed three times for 5 min each in 75 mM phosphoric acid and once for 2 min in acetone and air-dried, and their radioactivity was determined in a -counter.

Akt1-- Four hundred µg of cell lysates was immunoprecipitated with 2 µg/ml of an anti-Akt1 antibody (Santa Cruz Biotechnology, Inc.; catalog number sc-1618) as described for the ERK assay. The beads were then washed twice in 1 ml of lysis buffer and twice in 1 ml of Akt wash buffer (20 mM Tris, pH 7.5, 10 mM MgCl₂, 0.1 mg/ml bovine serum albumin, 1 mM dithiothreitol, 1 µg/ml IP-20). Thirty-five µl of the last wash was left in the tube and mixed with 25 µl of Akt reaction mix (Akt wash buffer, 0.2 mM ATP, 0.2 mg/ml cross-tide peptide (GRPRTSSFAEG), 0.2 µCi/µl [³²P]ATP) and incubated for 20 min at 30 °C. The reaction was stopped with 10 µl of 0.5 M EDTA and spotted on P81 Whatman paper as described for the ERK assay.

p38-- p38 activity was measured exactly as described by Gerwins et al. (16).

Immunoblots-- 200-400 µg of cell lysate protein was subjected to SDS-7-10% polyacrylamide gel electrophoresis and transferred to nitrocellulose membranes. Blots were performed exactly as described (17).

Measurements of Caspase Activities-- Cells were lysed in 50 mM Tris, pH 7.4, 1 mM EDTA, 10 mM EGTA. Sixty µg of lysate proteins were incubated with 5 µM DEVD-7-amido-4-methylcoumarin (Bachem) in 1 ml of 50 mM Tris, pH 7.4, 1 mM EDTA, 10 mM EGTA for 20 min at 37 °C. Fluorescence was then monitored with an excitation wavelength of 380 nm and an emission wavelength of 460 nm. Fluorescence of the substrate alone was subtracted in each case.

Measurement of Apoptosis-- Cells (1-2 × 10⁶) were resuspended in 100 µl of incubation buffer (10 mM Hepes/NaOH, pH 7.4, 140 mM NaCl, 5 mM CaCl₂) containing 1 µg/ml propidium iodide (Sigma; P-4170) and a 1:50 dilution of Annexin-V-Flos solution (Boehringer Mannheim; catalog number 1828681) and incubated 15 min on ice. Four hundred µl of incubation buffer was then added, and the cells were sorted on a flow cytometer using 488-nm excitation and a 515-nm bandpass filter for fluorescence detection and a filter >560 nm for propidium iodide detection. Apoptotic cells were defined as green fluorescent positive and propidium iodide negative.

Plasmids-- Akt1.dn3 corresponds to the mouse Akt-1 cDNA (nucleotides 254-1729) subcloned into the pcDNA3 eukaryotic expression vector (InVitrogen). h_Cbl.dn3 corresponds to the human Cbl cDNA (nucleotides 10-2892) subcloned into pcDNA3. JNK1.rst corresponds to the human JNK11 cDNA in pRSET (InVitrogen). MEK1.rst corresponds to the mouse MEK1 cDNA (nucleotides 38-1254) in pRSETb. Raf1.rst corresponds to the human Raf1 cDNA (nucleotides 133-2977) in pRSETa. h_RasGAP.dn3 corresponds to the human RasGAP cDNA (clone 101) (nucleotides 1-3987) in pcDNA3. SEK1.rst corresponds to the mouse SEK1 cDNA (nucleotides 16-2292) in pRSETb, and MEKK1.dn3 corresponds to the mouse MEKK1 cDNA in pcDNA3.

In Vitro Translation-- Proteins were in vitro translated using the TNT® T7 coupled reticulocyte lysate system (Promega) as per the manufacturer's conditions. The plasmids used were Akt1.dn3, h_Cbl.dn3, JNK1.rst, MEK1.rst, Raf1.rst, h_RasGAP.dn3, SEK1.rst, and MEKK1.dn3. The cleavage assay of the in vitro translated proteins was performed in the buffer used to measure DEVD-directed caspase activity (see above).

	RESULTS

Top Abstract Introduction Procedures Results Discussion References

The fate of specific cellular proteins involved in the regulation of signal transduction during the apoptotic response was analyzed. Jurkat cells were treated with etoposide, a topoisomerase inhibitor; UV-C (254-nm) irradiation, which generates oxygen radicals and induces RNA/DNA damage; or anti-Fas antibodies that activate Fas. The apoptotic response was temporally defined for each stimulus by measuring annexin V positive cells and the activation of DEVD-directed caspases (Fig. 1). Both annexin V binding and caspase activation are well defined markers of apoptosis (18). In addition, Jurkat cells undergoing cell death showed morphological changes characteristic of apoptosis, including cytoplasmic shrinkage and nuclear condensation (data not shown). Fas ligation induced a rapid apoptosis as assessed by the appearance of annexin V binding at the cell surface after 15 min that reached a maximum after 1 h. UV-C (100 J/m²) irradiation and incubation with etoposide (30 µM) induced a slower cell death response that reached a maximum for both stimuli at approximately 8 h. The kinetics of DEVD-caspase activation paralleled the induction of annexin V binding to the cells.

View larger version (22K): [in this window] [in a new window]   Fig. 1.   Etoposide-, UV-, and Fas-mediated apoptosis in Jurkat cells. Jurkat cells were incubated with 30 µM etoposide or stimulated with anti-Fas IgM antibodies for the indicated periods of time at 37 °C. Alternatively, the cells were irradiated with 100 J/m2 of UV-C (254 nm) and incubated at 37 °C for the indicated periods of time. DEVD-directed caspase activity and annexin-V binding were then measured as described under "Experimental Procedures."

Immunoblot analysis was performed against lysates from cells treated with etoposide, UV-C, or Fas antibody for different times with antibodies directed against 35 proteins having functions involved in different signaling pathways (Fig. 2 and Table I). Of these proteins, the expression of 22 was not significantly altered during apoptosis. These included ERK1, ERK2, and the p85 and p110 subunits of PI3K that have been implicated in survival responses in different cell types (11, 14, 19) as well as components of the pro-apoptotic p38 and JNK MAPK pathways (JNK-1, SEK-1, p38 MAPK). Four proteins, phospholipase C-1, Src, 14-3-3, and 14-3-3 were partially cleaved during the apoptotic response. Proteolysis of these proteins occurred somewhat late in the apoptotic response. The fragments were clearly visible by immunoblotting, but the cleavage was incomplete and did not appear to significantly affect the amount of the full-length proteins.

View larger version (66K): [in this window] [in a new window]   Fig. 2.   Cleavage of a restricted set of signaling proteins in apoptotic Jurkat cells. Jurkat cells, treated as in Fig. 1, were lysed and analyzed by Western blot for the presence of the indicated proteins using the antibodies described in Table I. TRAF-1, tumor necrosis factor receptor-associated protein-1; PLC1, phospholipase C-1.

View this table: [in this window] [in a new window]   Table I Antibodies used in this study Rabbit serum antibodies were detected with protein A conjugated with horseradish peroxidase (1:4000 dilution, Zymed; 10-1023). Goat IgGs were detected with horseradish peroxidase-conjugated rabbit anti-goat antibodies (1:2000 dilution, Zymed; 61-1620). Mouse IgGs were detected with horseradish peroxidase-conjugated goat anti-mouse IgG (H + L) (1:4000 dilution, Bio-Rad; 170-6516).

Nine proteins showed essentially complete proteolysis during the apoptotic response. These proteins could be categorized into two groups based on their rate of cleavage following an apoptotic response. The first group is characterized by rapid cleavage after an apoptotic stimulus (extensive cleavage in 1 h of Fas stimulation). The prototypes of rapidly cleaved proteins are the caspases themselves, which are synthesized as inactive zymogens and are cleaved during their activation (3). The kinetics of ICH1_L (caspase-2) and CPP32 (caspase-3) cleavage are shown in Fig. 2. Of the proteins assayed, three major signal transduction proteins were cleaved as fast as ICH1_L and CPP32 (Fig. 2). These included the previously characterized caspase substrates MEKK1 and focal adhesion kinase (5, 6, 20). Surprisingly, we found that the 120-kDa RasGAP protein was also rapidly cleaved with a similar time course as that for caspase activation. The second group of signaling proteins were cleaved with slower kinetics in Fas-stimulated cells (extensive cleavage detected only after 2 h of Fas stimulation). These were the adapter proteins Cbl and Cbl-b and the serine-threonine kinases Raf-1 and Akt-1. Etoposide and UV-C, which are slow stimulators of apoptosis compared with anti-Fas antibodies (Fig. 1), induced the cleavage of the proteins of both groups between 8 and 16 h and between 4 and 8 h of treatment, respectively (Fig. 2). Because of their involvement in the PI3K/Akt and the ERK MAPK pathways, shown to have survival functions in different cell types (11, 14, 19), Cbl and Cbl-b (which can bind PI3K), Raf-1 (the upstream regulator of the ERKs), and Akt-1 each have potential anti-apoptotic functions.

The cleavage of RasGAP, Raf-1, Cbl/Cbl-b, and Akt-1 in response to apoptotic stimuli has not been described previously. To demonstrate the generality of these signaling proteins as substrates for proteolysis during apoptosis, their cleavage in U937 cells exposed to UV-C was examined (Fig. 3). RasGAP is cleaved with a similar time course as that for CPP32. Cbl/Cbl-b, Raf-1, and Akt-1 were also cleaved but with slower kinetics. As controls, the dual specificity phosphatase, MAPK phosphatase-1, and the p110 subunit of PI3K were not degraded during the U937 cell apoptotic response.

View larger version (31K): [in this window] [in a new window]   Fig. 3.   Cleavage of RasGAP, CPP32, Cbl, Cbl-b, Raf-1, and Akt-1 in UV-C-irradiated U937 cells. U937 cells were irradiated with 100 J/m2 of UV-C (254 nm) and incubated for the indicated periods of time at 37 °C. The presence of the indicated proteins was then detected as in Fig. 2.

The cleavage of proteins during the apoptotic response is highly restricted and is not a general degradation of cellular proteins. Using mild (0.5% TX-100-containing buffer) to strong (2% SDS-containing buffer) extraction procedures, no difference in Coomassie-stained protein profiles is observed between lysates from control and apoptotic Jurkat cells (Fig. 4A). However, selective cleavage of proteins did occur as shown in the immunoblots in Fig. 4B (RasGAP is cleaved, while CD45 or phospholipase C-1 are unaffected).

View larger version (67K): [in this window] [in a new window]   Fig. 4.   Use of different lysis buffer to detect protein cleavage in apoptotic cells. Jurkat cells were stimulated or not with anti-Fas IgM antibodies and incubated at 37 °C for 1 h. The cells were then lysed in TX-100 lysis buffer, in radioimmune precipitation (RIPA) buffer (50 mM Hepes, pH 7.4, 150 mM NaCl, 1% Nonidet P-40, 0.1% deoxycholate, 0.1% SDS, 100 µM sodium vanadate, 0.05 mM ZnCl2, 2 mM EDTA) or in 1× sample buffer (60 mM Tris, pH 6.8, 720 mM -mercaptoethanol, 10% glycerol, 20 mg/ml SDS, 10 µg/ml bromphenol blue) and boiled for 5 min (Hot SDS). One hundred µg of proteins was loaded on a 10% polyacrylamide gel. A, Coomassie staining of the gel. B, the presence of CD45, phospholipase C-1 (PLC1), and RasGAP in the cell lysates was detected by Western blot analysis.

To define whether the cleavage of RasGAP, Cbl/Cbl-b, Raf-1, and Akt-1 resulted from caspase activation, Jurkat cells were incubated with or without cell-permeable caspase inhibitors during Fas ligation-induced apoptosis (Fig. 5A). The caspase inhibitor effectively blocked the cleavage of each of the proteins tested, including MEKK1, a defined caspase substrate (4, 6). Similarly, U937 cells overexpressing Bclx_L, which has anti-apoptotic functions and is involved in the regulation of caspase activation (21, 22), also blocked cleavage of RasGAP, Akt-1, Cbl, Raf-1, and CPP32 in response to UV-C irradiation (Fig. 5B). Thus, the activation of caspases is required for the cleavage and degradation of these proteins in both Jurkat and U937 cells.

View larger version (39K): [in this window] [in a new window]   Fig. 5.   Cleavage of RasGAP, Akt-1, Cbl/Cbl-b, and Raf-1 in apoptotic cells is dependent on caspase activation. A, Jurkat cells were left untreated or stimulated with anti-Fas IgM antibodies in the presence or absence of 20 µM Ac-YVAD-CMK (Bachem) for 1 h (MEKK1, RasGAP, and Cbl/Cbl-b) or 2 h (Akt-1 and Raf-1) at 37 °C. The cells were then lysed, and the presence of the indicated proteins was determined by Western blot analysis. Similar results were obtained with 20 µM of the Z-DEVD-FMK inhibitor (Enzyme Systems Products). B, U937 parental cells and cells stably expressing BclxL were irradiated with 100 J/m2 of UV-C (254 nm) and incubated 8 h at 37 °C. The presence of the indicated proteins was determined as in panel A.

Lysates from Fas-activated Jurkat cells have proven to be a good system for the assay of DEVD-directed caspases (4, 18). Therefore, lysates were prepared from control and Fas-ligated T cells to which [³⁵S]methionine labeled in vitro translation products for MEKK1, RasGAP, Akt-1, Cbl, Raf-1, and three control proteins shown not to be degraded during apoptosis, SEK1, MEK1, and JNK1. Only MEKK1 and RasGAP were shown to be proteolyzed when added to the lysate from Fas-activated cells (Fig. 6). Purified CPP32 generated the same RasGAP fragments as those generated by lysates from apoptotic Jurkat cells (data not shown). This defines RasGAP as a DEVD-directed caspase substrate, as is MEKK1. Cbl, Akt-1, and Raf-1 were not proteolyzed in lysates from Fas-activated Jurkat cells, indicating that they are not cleaved by the caspases proteolyzing RasGAP and MEKK1 in the in vitro conditions used here. Their cleavage is, however, dependent on the activation of caspases as demonstrated in Fig. 5.

View larger version (47K): [in this window] [in a new window]   Fig. 6.   RasGAP is a DEVD-directed caspase substrate. The indicated in vitro translated proteins were incubated for 6 h with 6 µg of lysates prepared from untreated Jurkat cells () or from Jurkat cells stimulated for 1 h with anti-Fas antibodies (+). Full-length proteins are indicated with arrows, and fragments are represented by arrowheads.

To assess the significance of protein cleavage on signaling pathways, we measured the activity of the ERK, JNK, and p38 MAPK pathways in Fas-stimulated Jurkat cells (Fig. 7A). The ERK pathway was transiently stimulated by anti-Fas antibodies as reported previously (23), reaching a maximum 1 h following Fas stimulation and returning to basal levels 2 h following Fas stimulation. A similar pattern of activation was detected for Raf-1 (Fig. 7A). Among the components of the ERK MAPK pathway, only Raf-1 was cleaved in response to Fas stimulation. Neither B-Raf, MEK1, MEK2, ERK1, nor ERK2 was cleaved in apoptotic cells (Fig. 2). The decline in the activity of Raf-1 and the ERK MAPK pathway correlated with the cleavage of Raf-1 in response to Fas stimulation. To determine whether the reduced activity of the ERK proteins in Fas-stimulated cells resulted from a general down-regulation mechanism, Jurkat cells were stimulated with anti-CD28 antibodies for 5 min after different periods of time following Fas stimulation. Fig. 7B shows that the ERK pathway could be stimulated by CD28 cross-linking (24). The ERK pathway could still be stimulated over the Fas-induced response by the anti-CD28 antibody 1 h after Fas cross-linking. However, at later time points, when the Fas-induced ERK response started to decline, the anti-CD28 antibody had no stimulatory effect on the ERK pathway (Fig. 7, compare A and B). There is thus a general impairment of the ERK pathway in Fas-stimulated Jurkat cells. These results suggest that the cleavage of Raf-1 contributes to the shut-off of the ERK MAPK pathway in apoptotic Jurkat cells.

View larger version (22K): [in this window] [in a new window]   Fig. 7.   Activation of MAPK pathways, Raf-1, and Akt-1 in Fas-stimulated Jurkat cells. A, Jurkat cells were stimulated with anti-Fas IgM antibodies and incubated at 37 °C for different periods of time. The cells were then lysed, and the activities of the ERK, Raf-1, Akt1, p38, and JNK kinases were measured. B, Jurkat cells were stimulated as in panel A. At the indicated times, the cells were incubated for 5 min with 500 ng/ml anti-CD28 IgG1 antibodies (clone L293, Beckton Dickinson) and 1 µg/ml goat anti-mouse antibodies (Santa Cruz Biotechnology; sc-2005). The cells were then lysed, and the ERK activity was measured. The graph shows the increase of ERK activity induced by CD28 activation over the ERK activity induced by Fas stimulation.

Another potential survival pathway, the PI3K-Akt pathway, appears also to be compromised in apoptotic cells, as assessed by decreased activity of the Akt-1 protein in Fas-stimulated Jurkat cells (Fig. 7A). The decline of the Akt-1 activity follows a similar time course to its degradation after Fas ligation (compare Figs. 2 and 7A). The PI3K subunits were not cleaved in apoptotic cells (Fig. 2). This suggests that the PI3K-Akt pathway is down-regulated as a consequence of Akt1 cleavage.

In contrast, the activities of the p38 and the JNK MAPK pathways remain high even 2 h following Fas ligation (Fig. 7A). Among the components of these pathways that we tested for cleavage in apoptotic cells (MEKK1, MEKK2, SEK-1, JNK-1, p38 MAPK), only MEKK1 was cleaved (Fig. 2). However, this cleavage event does not destroy the kinase activity of the protein but rather leads to an amplification of the apoptotic response (4, 6). Thus, no cleavage event could be determined to negatively affect the activation of the JNK and the p38 MAPK pathways in Fas-stimulated cells. These results demonstrate a selectivity in the turn-off of the ERK and Akt pathways in response to an apoptotic stimulus. Both JNK and p38 have been proposed to have pro-apoptotic functions in different cell types (10), and their sustained activation when ERK and Akt activities have been lost could contribute to the apoptotic signaling in response to Fas ligation.

	DISCUSSION

Top Abstract Introduction Procedures Results Discussion References

The commitment of a cell to mitosis, differentiation, or apoptosis requires the integration of numerous inputs involving multiple signal transduction pathways. For each of these responses, check points during the progression to the final phenotype ensure the proper outcome (10). Thus, the orchestration of signal transduction pathways controls the response of a cell to extracellular inputs. Relative to apoptosis, different signaling pathways can contribute to enhancing the death response or inhibit apoptosis and contribute to cell survival (10, 11). A common end point in the commitment to apoptosis is the activation of caspases. Inhibition of caspases generally inhibits apoptosis. However, numerous caspases have been identified, and no one caspase has been shown to be required for apoptosis in all tissues. The prediction is that different caspases differentially contribute to the apoptotic program in different cell types. For example, the targeted deletion of CPP32 (caspase-3) causes loss of apoptosis in the developing brain of mice, but thymic selection appears normal (25), suggesting that CPP32 is necessary for normal brain development but not T cell selection.

Caspase-dependent cleavage can inactivate proteins involved in repair mechanisms or the cell cycle (such as poly(ADP-ribose) polymerase, DNA-dependent protein kinase, Rb, protein kinase C), lead to the degradation of structural proteins (such as lamins and actins), or activate proteins to become proapoptotic (such as p21-activated kinase, MEKK1, gelsolin, and the caspases themselves) (2, 4, 6, 7, 9). Because of the role of various intracellular pathways in the control of the apoptotic response (10), we were interested in determining whether signaling proteins could be cleaved in apoptotic cells. We have found that among 30 proteins with signaling functions, only a limited set is cleaved in apoptotic Jurkat T cell lymphomas and U937 myeloid cells. Our findings show that component members of signaling pathways involved in cell growth and survival can be cleaved in cells undergoing cell death. We demonstrate, for the first time, that RasGAP, Cbl/Cbl-b, Akt-1, and Raf-1 are degraded during apoptosis. The loss of these proteins during apoptosis is consistent with a hypothesis that the caspases turn off survival signals in addition to activating death signals. For example, Akt-1 and the ERK pathway activated by Raf-1 have clearly been shown to promote survival in different cell types (11, 14, 19). Our studies demonstrate that the ERK and Akt activities are inhibited during apoptosis. The role of Cbl/Cbl-b degradation is less clear. Cbl has been shown to function as an adapter protein and to bind PI3K (26). Thus, Cbl can presumably lead to the activation of Akt-1, a kinase mediating survival responses in several cell types (11). The role of RasGAP cleavage is also not immediately obvious. However, Ras, even though it can regulate Raf-1 and lead to ERK activation, has been shown to enhance apoptotic responses (10, 27). Also, targeted disruption of RasGAP has been shown to result in enhanced apoptosis in the brains of developing mouse embryos (28), consistent with the idea that loss of RasGAP contributes positively to apoptosis.

Of the five proteins, RasGAP, Cbl/Cbl-b, Raf-1, and Akt-1, that we newly describe as being degraded during apoptosis, only RasGAP was cleaved in vitro using Jurkat cell lysates that contain high DEVD-directed caspase activity. In the RasGAP primary amino acid sequence, there is the sequence ⁴⁵²DTVD⁴⁵⁵G that would be efficiently recognized by DEVD-directed caspases. Cleavage at this site would generate a N-terminal fragment that is almost identical to a RasGAP construct that has been shown to alter cytoskeletal structure and cell adhesion (29). Thus, the caspase-dependent cleavage of RasGAP may generate a fragment that contributes to cell detachment, a feature often associated with cell death. Cell detachment is physiologically important because it facilitates removal of apoptotic cells by macrophages (30). The sequence in MEKK1 recognized by caspase-3-like proteases is identical (4, 6). Both MEKK1 and RasGAP are cleaved with kinetics similar to CPP32 (caspase-3) cleavage and activation, indicating that they are primary substrates for caspases. We are currently determining whether the RasGAP aspartic acid at residue 455 is indeed the caspase cleavage site and if RasGAP cleavage contributes to apoptosis.²

The fact that Cbl/Cbl-b, Akt-1, and Raf-1 were not cleaved in the in vitro assay using Jurkat lysates indicates that they are not DEVD-directed caspase substrates. They could be substrates either for other caspases or for non-caspase proteases that are not readily assayed in lysates from Fas-stimulated Jurkat cells. We are currently addressing this question biochemically, but in both Jurkat and U937 cells caspase activation is required for Cbl/Cbl-b, Akt-1, and Raf-1 degradation during apoptosis.

In summary, we have identified five additional proteins that are degraded during apoptosis. One of these proteins, RasGAP, is a newly identified DEVD-directed caspase substrate. Cleavage of Raf-1 and Akt-1 inhibits their kinase activity, which may explain why the potential survival signals involving ERK and Akt activity are turned off. Components of the JNK and the p38 MAPK pathways, known to have pro-apoptotic functions in Jurkat cells (31-34), were not cleaved during apoptosis; the exception is MEKK1, whose cleavage does not inhibit its activity. This suggests that caspases function in part to inhibit potential survival signals, allowing the death signals to predominate. The results are consistent with different sets of proteins being cleaved at various stages of the apoptotic response using different proteases in a temporally ordered manner to commit cells to death.

	ACKNOWLEDGEMENTS

We thank Cindy Knall and Mathew Jarpe for critical reading of the manuscript. We thank Steve Anderson for the pUC plasmid containing the human Cbl cDNA, Andrius Kaslauskas for the pUC plasmid containing the human RasGAP cDNA, Donald Kufe for U937 cells overexpressing Bclx_L, Lynn Heasley for Raf.rst, and Micheal Falta for the generous gift of the anti-CD28 antibody.

	FOOTNOTES

^* The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

^¶ Recipient of Swiss National Science Foundation Grant 823A-042980.

The first two authors contributed equally to this work.

To whom correspondence should be addressed: Gary L. Johnson, Division of Basic Sciences, National Jewish Medical and Research Center, 1400 Jackson St., Denver, CO 80206. Tel.: 303-398-1504; Fax: 303-398-1225; E-mail: johnsong{at}njc.org.

¹ The abbreviations used are: MEKK, MEK kinase; MEK, MAPK/ERK kinase; ERK, extracellular signal-regulated kinase; HOG, high osmolarity glycerol response; JNK, c-Jun N-terminal kinase; MAPK, mitogen-activated protein kinase; PI3K, phosphatidylinositol-3 kinase, RasGAP, Ras GTPase activating protein; SEK, stress-activated protein kinase/ERK kinase; UV-C, ultraviolet-C.

² C. Widmann, manuscript in preparation.

	REFERENCES

Top Abstract Introduction Procedures Results Discussion References

1. Alnemri, E. S., Livingston, D. J., Nicholson, D. W., Salvesen, G. S., Thornberry, N. A., Wong, W. W., Yuan, J. (1996) Cell 87, 171[CrossRef][Medline] [Order article via Infotrieve]
2. Nicholson, D. W., and Thornberry, N. A. (1997) Trends Biochem. Sci. 22, 299-306[CrossRef][Medline] [Order article via Infotrieve]
3. Salvesen, G. S., and Dixit, V. M. (1997) Cell 91, 443-446[CrossRef][Medline] [Order article via Infotrieve]
4. Widmann, C., Gerwins, P., Lassignal Johnson, N., Jarpe, M. B., and Johnson, G. L. (1998) Mol. Cell. Biol. in press,
5. Widmann, C., Lassignal Johnson, N., Gardner, A. M., Smith, R. J., and Johnson, G. L. (1997) Oncogene 15,
6. Cardone, M., Salvesen, G. S., Widmann, C., Johnson, G. L., Frisch, S. M. (1997) Cell 90, 315-323[CrossRef][Medline] [Order article via Infotrieve]
7. Kothakota, S., Azuma, T., Reinhard, C., Klippel, A., Tang, J., Chu, K., McGarry, T. J., Kirschner, M. W., Koths, K., Kwiatkowski, D. J., Williams, L. T. (1997) Science 278, 294-298[Abstract/Free Full Text]
8. Emoto, Y., Manome, Y., Meinhardt, G., Kisaki, H., Kharbanda, S., Robertson, M., Ghayur, T., Wong, W. W., Kamen, R., Weichselbaum, R., Kufe, D. (1995) EMBO J. 14, 6148-6156[Medline] [Order article via Infotrieve]
9. Rudel, T., and Bokoch, G. M. (1997) Science 276, 1571-1574[Abstract/Free Full Text]
10. Jarpe, M. B., Widmann, C., Knall, C., Schlesinger, T. K., Gibson, S., Yujuri, T., Fanger, G. R., Gelfand, E. G., and Johnson, G. L. (1998) Oncogene in press,
11. Franke, T. F., Kaplan, D. R., and Cantley, L. C. (1997) Cell 88, 435-437[CrossRef][Medline] [Order article via Infotrieve]
12. Datta, S. R., Dudek, H., Tao, X., Masters, S., Fu, H., Gotoh, Y., and Greenberg, M. E. (1997) Cell 91, 231-241[CrossRef][Medline] [Order article via Infotrieve]
13. del Peso, L., Gonzalez-Garcia, M., Page, C., Herrera, R., and Nunez, G. (1997) Science 278, 687-689[Abstract/Free Full Text]
14. Gardner, A. M., and Johnson, G. L. (1996) J. Biol. Chem. 271, 14560-14566[Abstract/Free Full Text]
15. Hibi, M., Lin, A., Smeal, T., Minden, A., and Karin, M. (1993) Genes Develop. 7, 2135-2148[Abstract/Free Full Text]
16. Gerwins, P., Blank, J. L., and Johnson, G. L. (1997) J. Biol. Chem. 272, 8288-8295[Abstract/Free Full Text]
17. Widmann, C., Dolci, W., and Thorens, B. (1995) Biochem. J. 310, 203-214
18. Toyoshima, F., Moriguchi, T., and Nishida, E. (1997) J. Cell Biol. 139, 1005-1015[Abstract/Free Full Text]
19. Xia, Z., Dickens, M., Raingeaud, J., Davis, R. J., Greenberg, M. E. (1995) Science 270, 1326-1331[Abstract/Free Full Text]
20. Wen, L.-P., Fahrni, J. A., Troie, S., Guan, J.-L., Orth, K., and Rosen, G. D. (1997) J. Biol. Chem. 272, 26056-26061[Abstract/Free Full Text]
21. Rao, L., and White, E. (1997) Curr. Opin. Genet. Dev. 7, 52-58[CrossRef][Medline] [Order article via Infotrieve]
22. Vander Heiden, M. G., Chandel, N. S., Williamson, E. K., Schumacker, P. T., Thompson, C. B. (1997) Cell 91, 627-637[CrossRef][Medline] [Order article via Infotrieve]
23. Goillot, E., Raingeaud, J., Ranger, A., Tepper, R. I., Davis, R. J., Harlow, E., Sanchez, I. (1997) Proc. Natn. Acad. Sci. U. S. A. 94, 3302-3307[Abstract/Free Full Text]
24. August, A., and Dupont, B. (1995) Tissue Antigens 46, 155-162[Medline] [Order article via Infotrieve]
25. Kuida, K., Zheng, T. S., Na, S., Kuan, C.-y., Yang, D., Karasuyama, H., Rakic, P., and Flavell, R. A. (1996) Nature 384, 368-372[CrossRef][Medline] [Order article via Infotrieve]
26. Meisner, H., Conway, B. R., Hartley, D., and Czech, M. P. (1995) Mol. Cell. Biol. 15, 3571-3578[Abstract]
27. Mayo, M. W., Wang, C.-Y., Cogswell, P. C., Rogers-Graham, K. S., Lowe, S. W., Der, C. J., Baldwin, A. S. J. (1997) Science 278, 1812-1815[Abstract/Free Full Text]
28. Henkemeyer, M., Rossi, D. J., Holmyard, D. P., Puri, M. C., Mbamalu, G., Harpal, K., Shih, T. S., Jacks, T., Pawson, T. (1995) Nature 377, 695-701[CrossRef][Medline] [Order article via Infotrieve]
29. McGlade, J., Brunkhorst, B., Anderson, D., Mbamalu, G., Settleman, J., Dedhar, S., Rozakis-Adcock, M., Chen, L. B., Pawson, T. (1993) EMBO J. 12, 3073-3081[Medline] [Order article via Infotrieve]
30. Savill, J., Fadok, V., Henson, P., and Haslett, C. (1993) Immunol. Today 14, 131-136[CrossRef][Medline] [Order article via Infotrieve]
31. Chen, Y.-R., Meyer, C. F., and Tan, T.-H. (1996) J. Biol. Chem. 271, 631-634[Abstract/Free Full Text]
32. Juo, P., Kuo, C. J., Reynolds, S. E., Konz, R. F., Raingeaud, J., Davis, R. J., Biemann, H.-P., Blenis, J. (1997) Mol. Cell. Biol. 17, 24-35[Abstract]
33. Chen, Y.-R., Wang, X., Templeton, D., Davis, R. J., Tan, T.-H. (1996) J. Biol. Chem. 271, 31929-31936[Abstract/Free Full Text]
34. Huang, S., Jiang, Y., Li, Z., Nishida, E., Mathias, P., Lin, S., Ulevitch, R. J., Nemerow, G. R., Han, J. (1997) Immunity 6, 739-749[CrossRef][Medline] [Order article via Infotrieve]
35. Valius, M., Secrist, J., and Kazlauskas, A. (1995) Mol. Cell. Biol. 15, 3058-3071[Abstract]

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				D. Scharner, L. Rossig, G. Carmona, E. Chavakis, C. Urbich, A. Fischer, T.-B. Kang, D. Wallach, Y. J. Chiang, Y. L. Deribe, et al. Caspase-8 Is Involved in Neovascularization-Promoting Progenitor Cell Functions Arterioscler. Thromb. Vasc. Biol., April 1, 2009; 29(4): 571 - 578. [Abstract] [Full Text] [PDF]

				A. C. Klimowicz, S. A. Bisson, K. Hans, E. M. Long, H. C. Hansen, and S. M. Robbins The phytochemical piceatannol induces the loss of CBL and CBL-associated proteins Mol. Cancer Ther., March 1, 2009; 8(3): 602 - 614. [Abstract] [Full Text] [PDF]

				M. R. Junttila, S.-P. Li, and J. Westermarck Phosphatase-mediated crosstalk between MAPK signaling pathways in the regulation of cell survival FASEB J, April 1, 2008; 22(4): 954 - 965. [Abstract] [Full Text] [PDF]

				M. M. McKay and D. K. Morrison Caspase-dependent Cleavage Disrupts the ERK Cascade Scaffolding Function of KSR1 J. Biol. Chem., September 7, 2007; 282(36): 26225 - 26234. [Abstract] [Full Text] [PDF]

				D. Michod and C. Widmann TAT-RasGAP317-326 Requires p53 and PUMA to Sensitize Tumor Cells to Genotoxins Mol. Cancer Res., May 1, 2007; 5(5): 497 - 507. [Abstract] [Full Text] [PDF]

				C. Zihni, C. Mitsopoulos, I. A. Tavares, B. Baum, A. J. Ridley, and J. D. H. Morris Prostate-derived Sterile 20-like Kinase 1-{alpha} Induces Apoptosis: JNK- AND CASPASE-DEPENDENT NUCLEAR LOCALIZATION IS A REQUIREMENT FOR MEMBRANE BLEBBING J. Biol. Chem., March 2, 2007; 282(9): 6484 - 6493. [Abstract] [Full Text] [PDF]

				G. Martin, N. Cagnon, O. Sabido, B. Sion, G. Grizard, P. Durand, and R. Levy Kinetics of occurrence of some features of apoptosis during the cryopreservation process of bovine spermatozoa Hum. Reprod., February 1, 2007; 22(2): 380 - 388. [Abstract] [Full Text] [PDF]

				J. Ramos, M. Sirisawad, R. Miller, and L. Naumovski Motexafin gadolinium modulates levels of phosphorylated Akt and synergizes with inhibitors of Akt phosphorylation Mol. Cancer Ther., May 1, 2006; 5(5): 1176 - 1182. [Abstract] [Full Text] [PDF]

				J.-Y. Yang, J. Walicki, A. Abderrahmani, M. Cornu, G. Waeber, B. Thorens, and C. Widmann Expression of an Uncleavable N-terminal RasGAP Fragment in Insulin-secreting Cells Increases Their Resistance toward Apoptotic Stimuli without Affecting Their Glucose-induced Insulin Secretion J. Biol. Chem., September 23, 2005; 280(38): 32835 - 32842. [Abstract] [Full Text] [PDF]

				A. Suzuki, G.-i. Kusakai, Y. Shimojo, J. Chen, T. Ogura, M. Kobayashi, and H. Esumi Involvement of Transforming Growth Factor-{beta}1 Signaling in Hypoxia-induced Tolerance to Glucose Starvation J. Biol. Chem., September 9, 2005; 280(36): 31557 - 31563. [Abstract] [Full Text] [PDF]

				H. Okhrimenko, W. Lu, C. Xiang, N. Hamburger, G. Kazimirsky, and C. Brodie Protein Kinase C-{varepsilon} Regulates the Apoptosis and Survival of Glioma Cells Cancer Res., August 15, 2005; 65(16): 7301 - 7309. [Abstract] [Full Text] [PDF]

				E. A. Medina, R. R. Afsari, T. Ravid, S. S. Castillo, K. L. Erickson, and T. Goldkorn Tumor Necrosis Factor-{alpha} Decreases Akt Protein Levels in 3T3-L1 Adipocytes via the Caspase-Dependent Ubiquitination of Akt Endocrinology, June 1, 2005; 146(6): 2726 - 2735. [Abstract] [Full Text] [PDF]

				M. Hahn, W. Li, C. Yu, M. Rahmani, P. Dent, and S. Grant Rapamycin and UCN-01 synergistically induce apoptosis in human leukemia cells through a process that is regulated by the Raf-1/MEK/ERK, Akt, and JNK signal transduction pathways Mol. Cancer Ther., March 1, 2005; 4(3): 457 - 470. [Abstract] [Full Text] [PDF]

				J.-Y. Yang, D. Michod, J. Walicki, B. M. Murphy, S. Kasibhatla, S. J. Martin, and C. Widmann Partial Cleavage of RasGAP by Caspases Is Required for Cell Survival in Mild Stress Conditions Mol. Cell. Biol., December 1, 2004; 24(23): 10425 - 10436. [Abstract] [Full Text] [PDF]

				E. Hammar, G. Parnaud, D. Bosco, N. Perriraz, K. Maedler, M. Donath, D. G. Rouiller, and P. A. Halban Extracellular Matrix Protects Pancreatic {beta}-Cells Against Apoptosis: Role of Short- and Long-Term Signaling Pathways Diabetes, August 1, 2004; 53(8): 2034 - 2041. [Abstract] [Full Text] [PDF]

				J. V. Thottassery, Y. Sun, L. Westbrook, S. S. Rentz, M. Manuvakhova, Z. Qu, S. Samuel, R. Upshaw, A. Cunningham, and F. G. Kern Prolonged Extracellular Signal-Regulated Kinase 1/2 Activation during Fibroblast Growth Factor 1- or Heregulin {beta}1-Induced Antiestrogen-Resistant Growth of Breast Cancer Cells Is Resistant to Mitogen-Activated Protein/Extracellular Regulated Kinase Kinase Inhibitors Cancer Res., July 1, 2004; 64(13): 4637 - 4647. [Abstract] [Full Text] [PDF]

				Y. Murayama, J.-i. Miyagawa, K. Oritani, H. Yoshida, K. Yamamoto, O. Kishida, T. Miyazaki, S. Tsutsui, T. Kiyohara, Y. Miyazaki, et al. CD9-mediated activation of the p46 Shc isoform leads to apoptosis in cancer cells J. Cell Sci., July 1, 2004; 117(15): 3379 - 3388. [Abstract] [Full Text] [PDF]

				G. Martin, O. Sabido, P. Durand, and R. Levy Cryopreservation Induces an Apoptosis-Like Mechanism in Bull Sperm Biol Reprod, July 1, 2004; 71(1): 28 - 37. [Abstract] [Full Text] [PDF]

				K. A. Green, M. J. Naylor, E. T. Lowe, P. Wang, E. Marshman, and C. H. Streuli Caspase-mediated Cleavage of Insulin Receptor Substrate J. Biol. Chem., June 11, 2004; 279(24): 25149 - 25156. [Abstract] [Full Text] [PDF]

				B. Bartling, J.-Y. Yang, D. Michod, C. Widmann, R. Lewensohn, and B. Zhivotovsky RasGTPase-activating protein is a target of caspases in spontaneous apoptosis of lung carcinoma cells and in response to etoposide Carcinogenesis, June 1, 2004; 25(6): 909 - 921. [Abstract] [Full Text] [PDF]

				V. Benoit, A. Chariot, L. Delacroix, V. Deregowski, N. Jacobs, M.-P. Merville, and V. Bours Caspase-8-Dependent HER-2 Cleavage in Response to Tumor Necrosis Factor {alpha} Stimulation Is Counteracted by Nuclear Factor {kappa}B through c-FLIP-L Expression Cancer Res., April 15, 2004; 64(8): 2684 - 2691. [Abstract] [Full Text] [PDF]

				Y. J. Lee, C. J. Froelich, N. Fujita, T. Tsuruo, and J. H. Kim Reconstitution of Caspase-3 Confers Low Glucose-Enhanced Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Cytotoxicity and Akt Cleavage Clin. Cancer Res., March 15, 2004; 10(6): 1894 - 1900. [Abstract] [Full Text] [PDF]

				J.-E. Kim and S. R. Tannenbaum S-Nitrosation Regulates the Activation of Endogenous Procaspase-9 in HT-29 Human Colon Carcinoma Cells J. Biol. Chem., March 12, 2004; 279(11): 9758 - 9764. [Abstract] [Full Text] [PDF]

				W. Kim, S. Kook, D. J. Kim, C. Teodorof, and W. K. Song The 31-kDa Caspase-generated Cleavage Product of p130cas Functions as a Transcriptional Repressor of E2A in Apoptotic Cells J. Biol. Chem., February 27, 2004; 279(9): 8333 - 8342. [Abstract] [Full Text] [PDF]

				S. Pervin, R. Singh, W. A. Freije, and G. Chaudhuri MKP-1-Induced Dephosphorylation of Extracellular Signal-Regulated Kinase Is Essential for Triggering Nitric Oxide-Induced Apoptosis in Human Breast Cancer Cell Lines: Implications in Breast Cancer Cancer Res., December 15, 2003; 63(24): 8853 - 8860. [Abstract] [Full Text] [PDF]

				Y. Zhang, M. I. Dawson, Y. Ning, L. Polin, R. E. Parchment, T. Corbett, A. N. Mohamed, K.-C. Feng, L. Farhana, A. K. Rishi, et al. Induction of apoptosis in retinoid-refractory acute myelogenous leukemia by a novel AHPN analog Blood, November 15, 2003; 102(10): 3743 - 3752. [Abstract] [Full Text] [PDF]

				K. Gumireddy, L. N. Sutton, P. C. Phillips, and C. D. Reddy All-trans-Retinoic Acid-induced Apoptosis in Human Medulloblastoma: Activation of Caspase-3/Poly(ADP-ribose) Polymerase 1 Pathway Clin. Cancer Res., September 15, 2003; 9(11): 4052 - 4059. [Abstract] [Full Text] [PDF]

				S. Pervin, R. Singh, and G. Chaudhuri Nitric-Oxide-induced Bax Integration into the Mitochondrial Membrane Commits MDA-MB-468 Cells to Apoptosis: Essential Role of Akt Cancer Res., September 1, 2003; 63(17): 5470 - 5479. [Abstract] [Full Text] [PDF]

				W. Jia, C. Yu, M. Rahmani, G. Krystal, E. A. Sausville, P. Dent, and S. Grant Synergistic antileukemic interactions between 17-AAG and UCN-01 involve interruption of RAF/MEK- and AKT-related pathways Blood, September 1, 2003; 102(5): 1824 - 1832. [Abstract] [Full Text] [PDF]

				H. M. Zhang, J. Yuan, P. Cheung, H. Luo, B. Yanagawa, D. Chau, N. Stephan-Tozy, B. W. Wong, J. Zhang, J. E. Wilson, et al. Overexpression of Interferon-{gamma}-inducible GTPase Inhibits Coxsackievirus B3-induced Apoptosis through the Activation of the Phosphatidylinositol 3-Kinase/Akt Pathway and Inhibition of Viral Replication J. Biol. Chem., August 29, 2003; 278(35): 33011 - 33019. [Abstract] [Full Text] [PDF]

				J. Torres, J. Rodriguez, M. P. Myers, M. Valiente, J. D. Graves, N. K. Tonks, and R. Pulido Phosphorylation-regulated Cleavage of the Tumor Suppressor PTEN by Caspase-3: IMPLICATIONS FOR THE CONTROL OF PROTEIN STABILITY AND PTEN-PROTEIN INTERACTIONS J. Biol. Chem., August 15, 2003; 278(33): 30652 - 30660. [Abstract] [Full Text] [PDF]

				H. Doong, K. Rizzo, S. Fang, V. Kulpa, A. M. Weissman, and E. C. Kohn CAIR-1/BAG-3 Abrogates Heat Shock Protein-70 Chaperone Complex-mediated Protein Degradation: ACCUMULATION OF POLY-UBIQUITINATED Hsp90 CLIENT PROTEINS J. Biol. Chem., August 1, 2003; 278(31): 28490 - 28500. [Abstract] [Full Text] [PDF]

				C. D. Gardner, S. Eguchi, C. M. Reynolds, K. Eguchi, G. D. Frank, and E. D. Motley Hydrogen Peroxide Inhibits Insulin Signaling in Vascular Smooth Muscle Cells Experimental Biology and Medicine, July 1, 2003; 228(7): 836 - 842. [Abstract] [Full Text] [PDF]

				H. Liu, Y. Ma, S. M. Cole, C. Zander, K.-H. Chen, J. Karras, and R. M. Pope Serine phosphorylation of STAT3 is essential for Mcl-1 expression and macrophage survival Blood, July 1, 2003; 102(1): 344 - 352. [Abstract] [Full Text] [PDF]

				J. Won, D. Y. Kim, M. La, D. Kim, G. G. Meadows, and C. O. Joe Cleavage of 14-3-3 Protein by Caspase-3 Facilitates Bad Interaction with Bcl-x(L) during Apoptosis J. Biol. Chem., May 23, 2003; 278(21): 19347 - 19351. [Abstract] [Full Text] [PDF]

				D. Barila, A. Rufini, I. Condo, N. Ventura, K. Dorey, G. Superti-Furga, and R. Testi Caspase-Dependent Cleavage of c-Abl Contributes to Apoptosis Mol. Cell. Biol., April 15, 2003; 23(8): 2790 - 2799. [Abstract] [Full Text] [PDF]

				J.-A. Haefliger, T. Tawadros, L. Meylan, S. L. Gurun, M.-E. Roehrich, D. Martin, B. Thorens, and G. Waeber The scaffold protein IB1/JIP-1 is a critical mediator of cytokine-induced apoptosis in pancreatic {beta} cells J. Cell Sci., April 15, 2003; 116(8): 1463 - 1469. [Abstract] [Full Text] [PDF]

				D. S. Zatechka Jr, P. F. Kador, S. Garcia-Castineiras, and M. F. Lou Diabetes Can Alter the Signal Transduction Pathways in the Lens of Rats Diabetes, April 1, 2003; 52(4): 1014 - 1022. [Abstract] [Full Text] [PDF]

				J. A. Witowsky and G. L. Johnson Ubiquitylation of MEKK1 Inhibits Its Phosphorylation of MKK1 and MKK4 and Activation of the ERK1/2 and JNK Pathways J. Biol. Chem., January 10, 2003; 278(3): 1403 - 1406. [Abstract] [Full Text] [PDF]

				D. Martin, M. Salinas, N. Fujita, T. Tsuruo, and A. Cuadrado Ceramide and Reactive Oxygen Species Generated by H2O2 Induce Caspase-3-independent Degradation of Akt/Protein Kinase B J. Biol. Chem., November 1, 2002; 277(45): 42943 - 42952. [Abstract] [Full Text] [PDF]

				R. D. Erwert, R. K. Winn, J. M. Harlan, and D. D. Bannerman Shiga-like Toxin Inhibition of FLICE-like Inhibitory Protein Expression Sensitizes Endothelial Cells to Bacterial Lipopolysaccharide-induced Apoptosis J. Biol. Chem., October 18, 2002; 277(43): 40567 - 40574. [Abstract] [Full Text] [PDF]

				Y. Zhang, M. I. Dawson, R. Mohammad, A. K. Rishi, L. Farhana, K.-C. Feng, M. Leid, V. Peterson, X.-k. Zhang, M. Edelstein, et al. Induction of apoptosis of human B-CLL and ALL cells by a novel retinoid and its nonretinoidal analog Blood, September 26, 2002; 100(8): 2917 - 2925. [Abstract] [Full Text] [PDF]

				J. Xu, D. Liu, and Z. Songyang The Role of Asp-462 in Regulating Akt Activity J. Biol. Chem., September 13, 2002; 277(38): 35561 - 35566. [Abstract] [Full Text] [PDF]

				C.-Y. F. Huang, Y.-M. Wu, C.-Y. Hsu, W.-S. Lee, M.-D. Lai, T.-J. Lu, C.-L. Huang, T.-H. Leu, H.-M. Shih, H.-I Fang, et al. Caspase Activation of Mammalian Sterile 20-like Kinase 3 (Mst3). NUCLEAR TRANSLOCATION AND INDUCTION OF APOPTOSIS J. Biol. Chem., September 6, 2002; 277(37): 34367 - 34374. [Abstract] [Full Text] [PDF]

				B. H. Han, D. Xu, J. Choi, Y. Han, S. Xanthoudakis, S. Roy, J. Tam, J. Vaillancourt, J. Colucci, R. Siman, et al. Selective, Reversible Caspase-3 Inhibitor Is Neuroprotective and Reveals Distinct Pathways of Cell Death after Neonatal Hypoxic-ischemic Brain Injury J. Biol. Chem., August 9, 2002; 277(33): 30128 - 30136. [Abstract] [Full Text] [PDF]

				M. Gomez-Angelats and J. A. Cidlowski Invited Review: Cell Volume Control and Signal Transduction in Apoptosis Toxicol Pathol, August 1, 2002; 30(5): 541 - 551. [Abstract] [PDF]

				B. Kim and E. L. Feldman Insulin-like Growth Factor I Prevents Mannitol-induced Degradation of Focal Adhesion Kinase and Akt J. Biol. Chem., July 19, 2002; 277(30): 27393 - 27400. [Abstract] [Full Text] [PDF]

				L. Bordone and C. Campbell DNA Ligase III Is Degraded by Calpain during Cell Death Induced by DNA-damaging Agents J. Biol. Chem., July 12, 2002; 277(29): 26673 - 26680. [Abstract] [Full Text] [PDF]

				A. C. Chin, D. A. Teoh, K. G.-E. Scott, J. B. Meddings, W. K. Macnaughton, and A. G. Buret Strain-Dependent Induction of Enterocyte Apoptosis by Giardia lamblia Disrupts Epithelial Barrier Function in a Caspase-3-Dependent Manner Infect. Immun., July 1, 2002; 70(7): 3673 - 3680. [Abstract] [Full Text] [PDF]

				C. Scheller, S. Sopper, P. Chen, E. Flory, E. Koutsilieri, T. Racek, S. Ludwig, V. ter Meulen, and C. Jassoy Caspase Inhibition Activates HIV in Latently Infected Cells. ROLE OF TUMOR NECROSIS FACTOR RECEPTOR 1 AND CD95 J. Biol. Chem., May 3, 2002; 277(18): 15459 - 15464. [Abstract] [Full Text] [PDF]

				T. K. Schlesinger, C. Bonvin, M. B. Jarpe, G. R. Fanger, J.-R. Cardinaux, G. L. Johnson, and C. Widmann Apoptosis Stimulated by the 91-kDa Caspase Cleavage MEKK1 Fragment Requires Translocation to Soluble Cellular Compartments J. Biol. Chem., March 15, 2002; 277(12): 10283 - 10291. [Abstract] [Full Text] [PDF]

				E. M. Gibson, E. S. Henson, J. Villanueva, and S. B. Gibson MEK Kinase 1 Induces Mitochondrial Permeability Transition Leading to Apoptosis Independent of Cytochrome c Release J. Biol. Chem., March 15, 2002; 277(12): 10573 - 10580. [Abstract] [Full Text] [PDF]

				C. Choi, O. Kutsch, J. Park, T. Zhou, D.-W. Seol, and E. N. Benveniste Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Induces Caspase-Dependent Interleukin-8 Expression and Apoptosis in Human Astroglioma Cells Mol. Cell. Biol., February 1, 2002; 22(3): 724 - 736. [Abstract] [Full Text] [PDF]

				C. Yu, G. Krystal, L. Varticovksi, R. McKinstry, M. Rahmani, P. Dent, and S. Grant Pharmacologic Mitogen-activated Protein/Extracellular Signal-regulated Kinase Kinase/Mitogen-activated Protein Kinase Inhibitors Interact Synergistically with STI571 to Induce Apoptosis in Bcr/Abl-expressing Human Leukemia Cells Cancer Res., January 1, 2002; 62(1): 188 - 199. [Abstract] [Full Text] [PDF]

				J.-Y. Yang and C. Widmann Antiapoptotic Signaling Generated by Caspase-Induced Cleavage of RasGAP Mol. Cell. Biol., August 15, 2001; 21(16): 5346 - 5358. [Abstract] [Full Text] [PDF]

				G. M. O'Neill and E. A. Golemis Proteolysis of the Docking Protein HEF1 and Implications for Focal Adhesion Dynamics Mol. Cell. Biol., August 1, 2001; 21(15): 5094 - 5108. [Abstract] [Full Text] [PDF]

				H. M. McDaid and S. B. Horwitz Selective Potentiation of Paclitaxel (Taxol)-Induced Cell Death by Mitogen-Activated Protein Kinase Kinase Inhibition in Human Cancer Cell Lines Mol. Pharmacol., August 1, 2001; 60(2): 290 - 301. [Abstract] [Full Text] [PDF]

				C. M. van Golen, T. S. Schwab, K. M. W. Ignatoski, S. P. Ethier, and E. L. Feldman PTEN/MMAC1 Overexpression Decreases Insulin-like Growth Factor-I-mediated Protection from Apoptosis in Neuroblastoma Cells Cell Growth Differ., July 1, 2001; 12(7): 371 - 378. [Abstract] [Full Text] [PDF]

				C. Cerdan, E. Devilard, L. Xerri, and D. Olive The C-class chemokine lymphotactin costimulates the apoptosis of human CD4+ T cells Blood, April 15, 2001; 97(8): 2205 - 2212. [Abstract] [Full Text] [PDF]

				J. Grossmann, K. Walther, M. Artinger, S. Kiessling, and J. Schölmerich Apoptotic Signaling during Initiation of Detachment-induced Apoptosis ("Anoikis") of Primary Human Intestinal Epithelial Cells Cell Growth Differ., March 1, 2001; 12(3): 147 - 155. [Abstract] [Full Text]

				E. Asselin, G. B. Mills, and B. K. Tsang XIAP Regulates Akt Activity and Caspase-3-dependent Cleavage during Cisplatin-induced Apoptosis in Human Ovarian Epithelial Cancer Cells Cancer Res., March 1, 2001; 61(5): 1862 - 1868. [Abstract] [Full Text]

				C.-W. Chiang, G. Harris, C. Ellig, S. C. Masters, R. Subramanian, S. Shenolikar, B. E. Wadzinski, and E. Yang Protein phosphatase 2A activates the proapoptotic function of BAD in interleukin- 3-dependent lymphoid cells by a mechanism requiring 14-3-3 dissociation Blood, March 1, 2001; 97(5): 1289 - 1297. [Abstract] [Full Text] [PDF]

				K. Suzuki, T. Hasegawa, C. Sakamoto, Y.-M. Zhou, F. Hato, M. Hino, N. Tatsumi, and S. Kitagawa Cleavage of Mitogen-Activated Protein Kinases in Human Neutrophils Undergoing Apoptosis: Role in Decreased Responsiveness to Inflammatory Cytokines J. Immunol., January 15, 2001; 166(2): 1185 - 1192. [Abstract] [Full Text] [PDF]

				V. SEE, A.-L. BOUTILLIER, H. BITO, and J.-P. LOEFFLER Calcium/calmodulin-dependent protein kinase type IV (CaMKIV) inhibits apoptosis induced by potassium deprivation in cerebellar granule neurons FASEB J, January 1, 2001; 15(1): 134 - 144. [Abstract] [Full Text] [PDF]

				H. Y. Chang and X. Yang Proteases for Cell Suicide: Functions and Regulation of Caspases Microbiol. Mol. Biol. Rev., December 1, 2000; 64(4): 821 - 846. [Abstract] [Full Text] [PDF]

				H. Sasaki, Y. Sheng, F. Kotsuji, and B. K. Tsang Down-Regulation of X-linked Inhibitor of Apoptosis Protein Induces Apoptosis in Chemoresistant Human Ovarian Cancer Cells Cancer Res., October 1, 2000; 60(20): 5659 - 5666. [Abstract] [Full Text]

				S. Kharbanda, P. Pandey, T. Yamauchi, S. Kumar, M. Kaneki, V. Kumar, A. Bharti, Z.-M. Yuan, L. Ghanem, A. Rana, et al. Activation of MEK Kinase 1 by the c-Abl Protein Tyrosine Kinase in Response to DNA Damage Mol. Cell. Biol., July 15, 2000; 20(14): 4979 - 4989. [Abstract] [Full Text]

				S. S. BAE, D. K. PERRY, Y. S. OH, J. H. CHOI, S. H. GALADARI, T. GHAYUR, S. H. RYU, Y. A. HANNUN, and P.-G. SUH Proteolytic cleavage of phospholipase C-{gamma}1 during apoptosis in Molt-4 cells FASEB J, June 1, 2000; 14(9): 1083 - 1092. [Abstract] [Full Text]

				C. Bertolotto, J.-E. Ricci, F. Luciano, B. Mari, J.-C. Chambard, and P. Auberger Cleavage of the Serum Response Factor during Death Receptor-induced Apoptosis Results in an Inhibition of the c-FOS Promoter Transcriptional Activity J. Biol. Chem., April 21, 2000; 275(17): 12941 - 12947. [Abstract] [Full Text] [PDF]

				J. B. Klein, M. J. Rane, J. A. Scherzer, P. Y. Coxon, R. Kettritz, J. M. Mathiesen, A. Buridi, and K. R. McLeish Granulocyte-Macrophage Colony-Stimulating Factor Delays Neutrophil Constitutive Apoptosis Through Phosphoinositide 3-Kinase and Extracellular Signal-Regulated Kinase Pathways J. Immunol., April 15, 2000; 164(8): 4286 - 4291. [Abstract] [Full Text] [PDF]

				P. R. Turner, S. Mefford, S. Christakos, and R. A. Nissenson Apoptosis Mediated by Activation of the G Protein-Coupled Receptor for Parathyroid Hormone (PTH)/ PTH-Related Protein (PTHrP) Mol. Endocrinol., February 1, 2000; 14(2): 241 - 254. [Abstract] [Full Text]

				C. Hermann, B. Assmus, C. Urbich, A. M. Zeiher, and S. Dimmeler Insulin-Mediated Stimulation of Protein Kinase Akt : A Potent Survival Signaling Cascade for Endothelial Cells Arterioscler. Thromb. Vasc. Biol., February 1, 2000; 20(2): 402 - 409. [Abstract] [Full Text] [PDF]

				D. M. Rose, P. M. Cardarelli, R. R. Cobb, and M. H. Ginsberg Soluble VCAM-1 binding to alpha 4 integrins is cell-type specific and activation dependent and is disrupted during apoptosis in T cells Blood, January 15, 2000; 95(2): 602 - 609. [Abstract] [Full Text] [PDF]

				F. Chai, A. Evdokiou, G.P. Young, and P.D. Zalewski Involvement of p21Waf1/Cip1 and its cleavage by DEVD-caspase during apoptosis of colorectal cancer cells induced by butyrate Carcinogenesis, January 1, 2000; 21(1): 7 - 14. [Abstract] [Full Text] [PDF]

				R. E. Bachelder, M. J. Ribick, A. Marchetti, R. Falcioni, S. Soddu, K. R. Davis, and A. M. Mercurio p53 Inhibits {alpha}6{beta}4 Integrin Survival Signaling by Promoting the Caspase 3-dependent Cleavage of AKT/PKB J. Cell Biol., November 29, 1999; 147(5): 1063 - 1072. [Abstract] [Full Text] [PDF]

				S. R. Datta, A. Brunet, and M. E. Greenberg Cellular survival: a play in three Akts Genes & Dev., November 15, 1999; 13(22): 2905 - 2927. [Full Text]

				S. Ruller, C. Stahl, G. Kohler, B. Eickhoff, J. Breder, M. Schlaak, and J. van der Bosch Sensitization of Tumor Cells to Ribotoxic Stress-induced Apoptotic Cell Death: A New Therapeutic Strategy Clin. Cancer Res., October 1, 1999; 5(10): 2714 - 2725. [Abstract] [Full Text] [PDF]

				A. D. Cristofano, P. Kotsi, Y. F. Peng, C. Cordon-Cardo, K. B. Elkon, and P. P. Pandolfi Impaired Fas Response and Autoimmunity in Pten+/ Mice Science, September 24, 1999; 285(5436): 2122 - 2125. [Abstract] [Full Text]

				S.-C. Hsu, M. A. Gavrilin, M.-H. Tsai, J. Han, and M.-Z. Lai p38 Mitogen-activated Protein Kinase Is Involved in Fas Ligand Expression J. Biol. Chem., September 3, 1999; 274(36): 25769 - 25776. [Abstract] [Full Text] [PDF]

				W. D. Jarvis, C. R. Johnson, F. A. Fornari, J. S. Park, P. Dent, and S. Grant Evidence That the Apoptotic Actions of Etoposide Are Independent of c-Jun/Activating Protein-1-Mediated Transregulation J. Pharmacol. Exp. Ther., September 1, 1999; 290(3): 1384 - 1392. [Abstract] [Full Text]

				D. G. Kirsch, A. Doseff, B. N. Chau, D.-S. Lim, N. C. de Souza-Pinto, R. Hansford, M. B. Kastan, Y. A. Lazebnik, and J. M. Hardwick Caspase-3-dependent Cleavage of Bcl-2 Promotes Release of Cytochrome c J. Biol. Chem., July 23, 1999; 274(30): 21155 - 21161. [Abstract] [Full Text] [PDF]

				B. B. Wolf and D. R. Green Suicidal Tendencies: Apoptotic Cell Death by Caspase Family Proteinases J. Biol. Chem., July 16, 1999; 274(29): 20049 - 20052. [Full Text] [PDF]

				M. E. Reyland, S. M. Anderson, A. A. Matassa, K. A. Barzen, and D. O. Quissell Protein Kinase C delta  Is Essential for Etoposide-induced Apoptosis in Salivary Gland Acinar Cells J. Biol. Chem., July 2, 1999; 274(27): 19115 - 19123. [Abstract] [Full Text] [PDF]

				M. T. Abreu-Martin, A. Chari, A. A. Palladino, N. A. Craft, and C. L. Sawyers Mitogen-Activated Protein Kinase Kinase Kinase 1 Activates Androgen Receptor-Dependent Transcription and Apoptosis in Prostate Cancer Mol. Cell. Biol., July 1, 1999; 19(7): 5143 - 5154. [Abstract] [Full Text] [PDF]

				A. Khwaja and L. Tatton Caspase-Mediated Proteolysis and Activation of Protein Kinase Cdelta Plays a Central Role in Neutrophil Apoptosis Blood, July 1, 1999; 94(1): 291 - 301. [Abstract] [Full Text] [PDF]

				S. Gibson, S. Tu, R. Oyer, S. M. Anderson, and G. L. Johnson Epidermal Growth Factor Protects Epithelial Cells against Fas-induced Apoptosis. REQUIREMENT FOR Akt ACTIVATION J. Biol. Chem., June 18, 1999; 274(25): 17612 - 17618. [Abstract] [Full Text] [PDF]

				Y. Fujio and K. Walsh Akt Mediates Cytoprotection of Endothelial Cells by Vascular Endothelial Growth Factor in an Anchorage-dependent Manner J. Biol. Chem., June 4, 1999; 274(23): 16349 - 16354. [Abstract] [Full Text] [PDF]

				S. N. Orlov, N. Thorin-Trescases, S. V. Kotelevtsev, J. Tremblay, and P. Hamet Inversion of the Intracellular Na+/K+ Ratio Blocks Apoptosis in Vascular Smooth Muscle at a Site Upstream of Caspase-3 J. Biol. Chem., June 4, 1999; 274(23): 16545 - 16552. [Abstract] [Full Text] [PDF]

				M. Huber, K. A. Watson, H.-C. Selinka, C. M. Carthy, K. Klingel, B. M. McManus, and R. Kandolf Cleavage of RasGAP and Phosphorylation of Mitogen-Activated Protein Kinase in the Course of Coxsackievirus B3 Replication J. Virol., May 1, 1999; 73(5): 3587 - 3594. [Abstract] [Full Text]

				T. Yujiri, G. R. Fanger, T. P. Garrington, T. K. Schlesinger, S. Gibson, and G. L. Johnson MEK Kinase 1 (MEKK1) Transduces c-Jun NH2-terminal Kinase Activation in Response to Changes in the Microtubule Cytoskeleton J. Biol. Chem., April 30, 1999; 274(18): 12605 - 12610. [Abstract] [Full Text] [PDF]

				S. Frutos, J. Moscat, and M. T. Diaz-Meco Cleavage of zeta PKC but Not lambda /iota PKC by Caspase-3 during UV-induced Apoptosis J. Biol. Chem., April 16, 1999; 274(16): 10765 - 10770. [Abstract] [Full Text] [PDF]

				S. Gibson, C. Widmann, and G. L. Johnson Differential Involvement of MEK Kinase 1 (MEKK1) in the Induction of Apoptosis in Response to Microtubule-targeted Drugs versus DNA Damaging Agents J. Biol. Chem., April 16, 1999; 274(16): 10916 - 10922. [Abstract] [Full Text] [PDF]

				B. R. Gastman, D. E. Johnson, T. L. Whiteside, and H. Rabinowich Caspase-mediated Degradation of T-Cell Receptor {{zeta}}-Chain Cancer Res., April 1, 1999; 59(7): 1422 - 1427. [Abstract] [Full Text] [PDF]

				M. M. Keane, S. A. Ettenberg, M. M. Nau, E. K. Russell, and S. Lipkowitz Chemotherapy Augments TRAIL-induced Apoptosis in Breast Cell Lines Cancer Res., February 1, 1999; 59(3): 734 - 741. [Abstract] [Full Text] [PDF]

				C. WIDMANN, S. GIBSON, M. B. JARPE, and G. L. JOHNSON Mitogen-Activated Protein Kinase: Conservation of a Three-Kinase Module From Yeast to Human Physiol Rev, January 1, 1999; 79(1): 143 - 180. [Abstract] [Full Text] [PDF]

				D. D. Bannerman, M. Sathyamoorthy, and S. E. Goldblum Bacterial Lipopolysaccharide Disrupts Endothelial Monolayer Integrity and Survival Signaling Events through Caspase Cleavage of Adherens Junction Proteins J. Biol. Chem., December 25, 1998; 273(52): 35371 - 35380. [Abstract] [Full Text] [PDF]

				J.-H. Yeh, S.-C. Hsu, S.-H. Han, and M.-Z. Lai Mitogen-activated Protein Kinase Kinase Antagonized Fas-associated Death Domain Protein-mediated Apoptosis by Induced FLICE-inhibitory Protein Expression J. Exp. Med., November 16, 1998; 188(10): 1795 - 1802. [Abstract] [Full Text] [PDF]

				H. Koh, K. H. Lee, D. Kim, S. Kim, J. W. Kim, and J. Chung Inhibition of Akt and Its Anti-apoptotic Activities by Tumor Necrosis Factor-induced Protein Kinase C-related Kinase 2 (PRK2) Cleavage J. Biol. Chem., October 27, 2000; 275(44): 34451 - 34458. [Abstract] [Full Text] [PDF]

				S. S. Hebert, A. Daviau, G. Grondin, M. Latreille, R. A. Aubin, and R. Blouin The Mixed Lineage Kinase DLK Is Oligomerized by Tissue Transglutaminase during Apoptosis J. Biol. Chem., October 13, 2000; 275(42): 32482 - 32490. [Abstract] [Full Text] [PDF]

				C. Bertolotto, L. Maulon, N. Filippa, G. Baier, and P. Auberger Protein Kinase C theta and epsilon Promote T-cell Survival by a Rsk-dependent Phosphorylation and Inactivation of BAD J. Biol. Chem., November 17, 2000; 275(47): 37246 - 37250. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Widmann, C. Articles by Johnson, G. L. Search for Related Content PubMed PubMed Citation Articles by Widmann, C. Articles by Johnson, G. L. Social Bookmarking                      What's this?