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(Received for publication, October 9, 1996)
From the ABSTRACT Cyclin-dependent kinase (Cdk) enzymes
are activated for entry into the S phase of the cell cycle. Elimination
of Cdk inhibitor protein p27Kip1 during the G1 to S
phase is required for the activation process. An inhibitor of
3-hydroxy-3-methylglutaryl-CoA reductase prevents its elimination and
leads to G1 arrest. Mevalonate and its metabolite, geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, restore
the inhibitory effect of pravastatin on the degradation of p27 and
allow Cdk2 activation. By the addition of geranylgeranyl pyrophosphate,
Rho small GTPase(s) are geranylgeranylated and translocated to
membranes during G1/S progression. The restoring effect of
geranylgeranyl pyrophosphate is abolished with botulinum C3 exoenzyme,
which specifically inactivates Rho. These results indicate (i) among
mevalonate metabolites, geranylgeranyl pyrophosphate is absolutely
required for the elimination of p27 followed by Cdk2 activation; (ii)
geranylgeranylated Rho small GTPase(s) promote the degradation of p27
during G1/S transition in FRTL-5 cells.
INTRODUCTION Transition from G1 to S phase in mammalian cells is
regulated by cyclin-dependent kinase 2 (Cdk2)1 and the cyclin E complex (1, 2).
p27Kip1, one of the Cdk inhibitors, governs Cdk2 activity
during the transition from G1 to S phase. The amount of p27
decreases as cells are induced to enter the cell cycle (3, 4); it has been demonstrated that the abundance of p27 in cells is regulated by
degradation by the ubiquitin-proteasome pathway (5); overexpression of
p27 can block cell cycle progression in G1 phase (6, 7); and p27 appears to be involved in G1 arrest caused by
transforming growth factor- p27 has been implicated in G1 arrest induced by an
inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (13, 14). Recent studies have also demonstrated that the ability of an
HMG-CoA reductase inhibitor to interfere with cell cycle progression
could be attributed to its ability to suppress the isoprenylation of
proteins, rather than its ability to interrupt cholesterol synthesis
(15, 16). However, the requirements of mevalonate and its metabolites
for the elimination of p27 and the activation of Cdk2 during the
transition from G1 to S phase have not yet been
examined.
The present investigation was performed in order to develop insights
into the regulation of p27 by mevalonate metabolite(s) during the
transition from G1 to S phase. For this purpose, we studied
the following questions: 1) which metabolite(s) of mevalonate are
active in promoting the elimination of p27? 2) Is protein isoprenylation involved in the elimination of p27? Rat thyroid FRTL-5
cells provide a suitable model for these studies, since their
progression from quiescence into the cell cycle is associated with a
burst of mevalonate synthesis caused by a large transcriptional activation of the HMG-CoA reductase gene by thyrotropin (TSH) (17).
EXPERIMENTAL PROCEDURES [3H]Geranylgeranyl pyrophosphate
([3H]GGPP) and [3H]farnesyl pyrophosphate
([3H]FPP) were purchased from DuPont NEN. GGPP and FPP
were purchased from Sigma. To make liposomes
containing each, an aliquot of a mixture of
dipalmitoylphosphatidylcholine (5 µmol) and GGPP or FPP (200 µg)
was added to a pear-shaped flask, and the solvent was removed by rotary
evaporation and then a vacuum pump. The dried lipid film was then
dispersed in 0.5 ml of phosphate-buffered saline. Warming the flask to
50 °C facilitates smooth dispersion. The liposomes were sonicated
and stored at 4 °C.
FRTL-5 cells (ATCC
CRL 8305), a strain of rat thyroid cells in continuous culture, were
grown in Coon's modified Ham's F-12 medium supplemented with 5% calf
serum and a six-hormone mixture of TSH (1 × 10 Anti-p27 (C-19), anti-Cdk2 (M2), anti-Rho A (119),
and anti-Rho B (119) antibodies were purchased from Santa Cruz
Biotechnology Inc. (Santa Cruz, CA). Immunoprecipitation and
immunoblotting were performed as described previously (18).
cDNA was prepared
from mouse liver poly(A)+ RNA using a cDNA synthesis
kit. The full-length mouse p27 cDNA was obtained using polymerase
chain reaction. Mouse liver cDNA was used as template, and the
following oligonucleotides were prepared as primers,
5 Recombinant mouse
p27-glutathione-S-transferase (GST) fusion protein was prepared using
cDNA containing the full length coding region for mouse p27. Cell
extracts were prepared as described by Pagano et al. (5).
Purified recombinant p27-GST fusion protein (1 µg) was incubated with
cell extracts in the presence of ATP and an ATP generating system. The
reaction products were analyzed by immunoblotting with anti-p27
antibody. Adenosine-5 RESULTS AND DISCUSSION The stimulation of quiescent FRTL-5 cells with TSH, insulin, and
5% calf serum resulted in the increase of thymidine incorporation into
DNA (Fig. 1A, lane 2 versus 1).
Immunoblotting revealed a coincident increase of the rapidly migrating,
phosphorylated form of Cdk2 as a single major 33-kDa band (Fig.
1B, lane 2 versus 1). The kinase activity associated with
Cdk2 was also stimulated (Fig. 1C, lane 2 versus 1). In
contrast, the level of p27 in quiescent FRTL-5 cells was high and
diminished after growth stimulation (Fig. 1D, lane 2 versus
1).
Pravastatin (1200 µM) inhibited growth-stimulated DNA
synthesis and induced G1 arrest in FRTL-5 cells (Fig.
1A, lane 3 versus 2 and Fig. 1E). Both the
activation of Cdk2 and the elimination of p27 during the transition
from G1 to S phase were also inhibited by pravastatin (Fig.
1, B-D, lane 3 versus 2). The presence of pravastatin
during the first 16 h of culture did not affect the activation of
Cdk2 nor the elimination of p27 in growth-stimulated FRTL-5 cells;
however the continued presence of pravastatin beyond 16 h
inhibited both the activation of Cdk2 and the elimination of p27 (Fig.
1, B and D, lanes 3-5 versus 2). The kinase
activity associated with Cdk2 had the same time course-dependence of
down-regulation in pravastatin-treated cells (Fig. 1C, lanes 3-5
versus 2).
Pravastatin did not increase p27 mRNA levels (Fig.
2A, lane 1 versus 2); instead, pulse-chase
analysis demonstrated that the half-life of p27 in pravastatin-treated
cells was nearly three times as long as its half-life in non-treated
cells (Fig. 2B, lanes 1-3 versus lanes 4-8). Since the
rate of p27 degradation was markedly slowed by the treatment with
pravastatin in the presence of constant amount of mRNA, the
accumulation of p27 could be attributed to reduced protein degradation
rather than to increased protein synthesis. We used extracts from
pravastatin-treated and nontreated cells as a source of ubiquitinating
enzymes and proteasomes. Purified recombinant mouse p27-GST fusion
protein was used as a substrate. We found that pravastatin treatment
had no significant effect on the degradation of p27 in cell extracts
(Fig. 2C, lanes 1-3 versus lanes 4-6). This indicates that
pravastatin may impair the degradation of p27 at the intracellular
processing step(s) proximal to the ubiquitination-proteasome
pathway.
Mevalonolactone (0.5 mg/ml) reversed pravastatin-induced inhibition of
DNA synthesis (Fig. 1A, lane 6 versus 3).
Pravastatin-induced inhibition of Cdk2 activation and p27 elimination
were reversed by the addition of mevalonolactone (Fig. 1, B-D,
lane 6 versus 3). Mevalonolactone only overcame the pravastatin
effect when added within the first 24 h following growth
stimulation (data not shown). In contrast, mevalonolactone did not
reverse pravastatin action at later times. Mevalonolactone did not
decrease p27 mRNA levels (Fig. 2A, lane 3).
Mevalonate acts as a isoprenyl precursor for farnesyl or geranylgeranyl
molecules which have an important signaling function (22). Exogenous
FPP and/or GGPP might be expected to counteract the effect of
pravastatin. Unfortunately, the experimental use of these compounds is
limited by their membrane impermeability and sensitivity to thiol
reagents present in the culture medium. Therefore, we introduced a
novel approach to evaluate the role of isoprenoids and protein
isoprenylation in the elimination of p27: the preparation of liposomes
of these isoprenoids.
All of the effects of pravastatin on DNA synthesis, Cdk2 activation,
the elimination of p27, and cell cycle progression were wholly reversed
by the addition of liposomes containing GGPP at the concentration of 10 µM (Fig. 1, A-D, lane 9 versus lane 7 or
3 and Fig. 1E). p27 mRNA levels were not
affected by GGPP (Fig. 2A, lane 6). Pulse-chase analysis of
the turnover rate of p27 demonstrated that the elongated half-life of
p27 in pravastatin-treated cells is shortened to the level of
nontreated cells by the addition of GGPP (Fig. 2B, lanes 4-8
versus 9-11). In contrast, the degradation of p27 in cell
extracts containing ubiquitinating enzymes and proteasomes was not
affected by pravastatin treatment and the supplementation with GGPP
(Fig. 2C, lanes 4-6 versus lanes 7-9). These data indicate
that GGPP is required for growth stimulation-induced p27 degradation
and does affect the availability of p27 to the ubiqutin-proteasome
pathway. The addition of FPP had no effect on the inhibitory action of
pravastatin (Fig. 1, A-D, lane 8 versus lane 7 or
3), although incorporation of [3H]FPP in
liposomes into FRTL-5 cells was almost equal to that of
[3H]GGPP (data not shown).
GGPP is biosynthetically derived from the single condensation of FPP
and IPP. Since IPP could not be synthesized in pravastatin-treated cells, FPP could not be converted to GGPP. These data indicate that
GGPP can rescue the pravastatin-induced G1 arrest in the absence of upstream intermediates of cholesterol biosynthesis and that
geranylgeranylated rather than farnesylated proteins are responsible
for inducing p27 elimination in FRTL-5 cells.
A class of geranylgeranylated small GTP-binding proteins, termed Rho
small GTPases, are proposed to be involved in the transition from
G1 to S phase (23, 24). Carboxyl-terminal lipids form part
of the hydrophobic signal that targets proteins to various membranes
within the cell. We, therefore, determined the subcellular distribution
of Rho small GTPases in pravastatin-treated cells with or without GGPP
supplementation. Immunoblot analysis of membrane and cytosolic
fractions for Rho A and Rho B revealed that GGPP promotes the
translocation of Rho A and Rho B from the cytoplasm to membranes during
the transition from G1 to S phase (Fig.
3A). In contrast, these proteins were
detected only in the cytosolic fraction in the absence of GGPP. The
immunoprecipitation of Rho A and Rho B in membrane fraction
demonstrated that these proteins were labeled by the supplementation
with [3H]GGPP in liposomes (Fig. 3B). High
performance liquid chromatography analysis of the lipids associated
with these proteins showed that these proteins were geranylgeranylated,
but not farnesylated (data not shown).
Botulinum C3 exoenzyme specifically inactivates Rho small GTPases
(25, 26, 27). The restoring effect of GGPP was abolished with C3 exoenzyme
(60 µg/ml) (Fig. 4). Thus it is reasonable to suggest
the possible involvement of Rho small GTPase(s) in the elimination of
p27. Consistent with this, Rho controls signal transduction pathways
that are essential for cell growth; and Rho is required for stress
fiber formation, transformation by oncogenic Ras, and signaling to
serum response factor by growth stimuli (28, 29, 30).
Our findings indicate that among mevalonate metabolites, GGPP, not FPP,
reversed the reduced p27 degradation induced by pravastatin. In the
presence of GGPP, Rho proteins necessary for S phase development are
also geranylgeranylated and translocated to membranes during G1/S progression. The restoring effect of GGPP was
abolished with botulinum C3 exoenzyme, which specifically inactivates
Rho proteins. Thus, geranylgeranylated protein(s), most likely Rho,
appear to play a critical role in regulating p27 elimination and Cdk2
activation during G1/S progression. Recently, a family of
target proteins of Rho small GTPases has been identified (31, 32). The
mechanisms underlying Rho-regulated p27 degradation require further
investigation.
FOOTNOTES Acknowledgments We thank S. Kurakata for pravastatin, Y. Soda
for technical advise, and M. Noda, S. Yoshida, M. Nishimura, and T. Tanaka for useful discussion. Special thanks to Y. Tsuchikawa, Y. Okuda, E. Miyagawa, M. Maemori, and K. Tanuma for their excellent
technical assistance.
REFERENCES
Volume 272, Number 1,
Issue of January 3, 1997
pp. 13-16
©1997 by The American Society for Biochemistry and Molecular Biology, Inc.
COMMUNICATION:
§,,,
,,,,,
Second Department of Internal Medicine,
Chiba University Medical School, Inohana-cho, Chuou-ku, Chiba 260, Japan, the ¶ Department of Cell Chemistry, Institute of Cellular
and Molecular Biology, Okayama University Medical School, Shikata-cho,
Okayama 700, Japan, the 
Banyu Tsukuba Research Institute in
Collaboration with Merck Research Laboratories, Okubo 3, Tsukuba
300-26, Japan, the ** Department of Internal Medicine, Chiba Municipal
Hospital, Yahagi, Chuou-ku, Chiba 260, Japan, the
Department of Pharmacology, Kyoto
University Faculty of Medicine, Yoshida, Sakyo-ku, Kyoto 606, Japan,
and the §§ Cell Regulation Section, Metabolic
Disease Branch, NIDDK, National Institutes of Health,
Bethesda, Maryland 20892
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS AND DISCUSSION
FOOTNOTES
Acknowledgments
REFERENCES
, cyclic AMP, and cell-cell contact
(6, 7, 8); conversely antisense vectors targeted to p27 mRNA increase the fraction of cells in S phase (9). In recent papers, it was
demonstrated that targeted disruption of the murine p27 gene enhances
growth of mice without an increase in the amounts of either growth
hormone or insulin-like growth factor-1 and that disruption of p27
function leads to striking enlargement of thymus, pituitary, and
adrenal glands and gonadal organs (10, 11, 12). These evidences suggest
that p27 might have a pivotal role in the control of cell
proliferation.
10
M), insulin (10 µg/ml), hydrocortisone (0.4 ng/ml), human
transferrin (5 µg/ml),
glycyl-L-histidyl-L-lysine acetate (10 ng/ml),
and somatostatin (10 ng/ml) (18). This medium is referred to as 6H
medium. For all experiments, cells were initially cultivated in 6H
medium for at least 3 days. As appropriate to individual experiments,
cells were then shifted to medium containing no TSH, no insulin, and
only 0.2% calf serum, which is referred to as 4H medium, for at least
5 days before use in individual experiments. Fluorescence-activated
cell sorter analysis revealed that the percentage of cells in
G0/G1 at that point is over 95%. These cells
are referred to as quiescent cells; the quiescent cells challenged with
6H medium are referred to as growth-stimulated cells. For whole cell
lysates, cells were collected and resuspended in cold lysis buffer
consisting of 50 mM HEPES at pH 7.0, 2 mM MgCl2, 250 mM NaCl, 0.1 mM EDTA,
0.1 mM EGTA, 1 mM dithiothreitol, 2 mM Na3VO4, 10 mM
Na4P2O7, 10 mM NaF,
0.1% Nonidet P-40, and a protease inhibitor mixture [10 µg/ml
p-amidinophenylmethanesulfonyl fluoride hydrochloride, 10 µg/ml pepstatin A, 10 µg/ml antipain, 10 µg/ml chymostatin, 10 µg/ml leupeptin, 10 µg/ml antipain]. The cells were allowed to
lyse on ice for 60 min. The homogenate was centrifuged for 5 min in a
Microfuge at 4 °C to obtain supernatants. For subcellular
fractionation, cells were disrupted by sonication in hypotonic buffer
(5 mM Tris-HCl, pH 7.0, 5 mM NaCl, 1 mM CaCl2, 2 mM EGTA, 1 mM MgCl2, and 2 mM dithiothreitol)
containing the protease inhibitor mixture and separated into crude
membrane- and cytosol-containing fractions by centrifugation
(100,000 × g, 30 min). For pulse-chase analysis, cells
were labeled with [35S]methionine and
[35S]cysteine for 2 h, 18-20 h after growth
stimulation, and then chased for 20-90 min. For labeling cells with
[3H]GGPP, cells were incubated for 36 h with 6H
medium in the presence of pravastatin, an HMG-CoA reductase inhibitor
(19) with supplementation of [3H]GGPP (18.5 MBq/µmol)
in liposomes. Pravastatin was kindly provided by Dr. S. Kurakata
(Sankyo Pharmaceutical Co., Ltd., Tokyo, Japan). Cdk2 activity was
determined reported by Turner et al. (20). [3H]Thymidine incorporation into DNA was determined as
reported previously (18). The cell cycle profiles of samples were
analyzed as previously reported (18).
-CGAGGAGGAAGATGTCAAACGT-3 and 5-AGCTGTTTACGTCTGGCGTCG-3. The
positive clone (595 base pairs) coded for nucleotides 1-595 of
mouse p27 cDNA as reported by Toyoshima et al. (7) and
contained the full-length coding region for the mouse p27. Northern
blot analysis was performed as described previously (21).
-(
-thio)triphosphate, a nonhydrolyzable ATP
analog, led to a reduction in p27 proteolysis. MG-115, an inhibitor of
the proteasome, but not E-64 also led to a reduction in p27
proteolysis. Purified recombinant GST was not degraded in cell
extracts.
Fig. 1.
Effect of mevalonate and its metabolites on
DNA synthesis, Cdk2 activation, the elimination of p27, and cell cycle
progression in FRTL-5 cells. Quiescent FRTL-5 cells were incubated
with 6H medium for 36 h with or without the noted additions;
quiescent cells in 4H medium (4H, lane 1); growth
stimulation with 6H medium (6H, lane 2); 6H plus pravastatin
(1200 µM, 0-36 h; 6H+Pra, lane 3) 6H plus
pravastatin (0-16 h; lane 4); 6H plus pravastatin (16-36 h; lane 5); 6H plus pravastatin (0-36 h) with mevalonate
(6H+Pra+Mev, lane 6); 6H plus pravastatin with control
liposomes (6H+Pra+(
)lipo, lane 7); 6H plus pravastatin
with farnesyl pyrophosphate in liposomes (6H+Pra+FPP, lane
8); 6H plus pravastatin with geranylgeranyl pyrophosphate in
liposomes (6H+Pra+GGPP, lane 9). Cell lysates (30 µg) were
analyzed by immunoblotting with antibodies against Cdk2 and p27.
[3H]Thymidine incorporation into DNA, Cdk2 activity
assay, and the analysis of cell cycle progression were performed as
described in the text. Data represent the average thymidine
incorporation into DNA (mean ± S.D. of three independent
experiments).
[View Larger Version of this Image (27K GIF file)]
Fig. 2.
Regulation of p27 metabolism by
geranylgeranyl pyrophosphate in FRTL-5 cells. A, effect of
pravastatin, mevalonate, and its metabolites on mRNA of p27 in
growth-stimulated FRTL-5 cells. Quiescent FRTL-5 cells were incubated
in 6H medium for 18 h. Northern blot analysis was performed as
described in the text: lane 1, 6H; lane 2, 6H + pravastatin; lane 3, 6H + pravastatin + mevalonate;
lane 4, 6H + pravastatin with control liposomes; lane
5, 6H + pravastatin + FPP; lane 6, 6H + pravastatin + GGPP. B, pulse-chase analysis of p27 in growth-stimulated
FRTL-5 cells was performed as described in the text: lanes
1-3, 6H; lanes 4-8, 6H + pravastatin
(6H+Pra); lanes 9-11, 6H + pravastatin + GGPP (6H+Pra+GGPP). C, in vitro ubiquitination and
proteasome-mediated degradation of p27 in cell extracts. Quiescent
FRTL-5 cells were incubated in 6H medium for 22 h and cell
extracts were prepared. The degradation of p27-GST fusion protein in
cell extracts was performed as described in the text: lanes
1-3, 6H; lanes 4-6, 6H + pravastatin
(6H+Pra); lanes 7-9, 6H + pravastatin + GGPP (6H+Pra+GGPP).
[View Larger Version of this Image (42K GIF file)]
Fig. 3.
Geranylgeranylation of Rho proteins during
G1/S transition. A, immunoblot analysis of Rho
proteins in membrane and cytosol fractions in growth-stimulated FRTL-5
cells. Quiescent FRTL-5 cells were incubated in 6H medium for 36 h
and crude membrane- and cytosol-containing fractions were prepared as
described in the text. Each sample (30 µg) was analyzed by
immunoblotting with antibodies against Rho A and Rho B: lane
1, 6H; lane 2, 6H + pravastatin; lane 3, 6H + pravastatin + mevalonate; lane 4, 6H + pravastatin + GGPP.
B, fluorography of immunoprecipitated
[3H]geranylgeranyl pyrophosphate-labeled Rho A and Rho B
in membrane fraction. Molecular size standards (in kilodaltons) are
indicated on the left. Arrows depict the
[3H]geranylgeranylated Rho proteins.
[View Larger Version of this Image (28K GIF file)]
Fig. 4.
Effect of botulinum C3 exoenzyme on
geranylgeranyl pyrophosphate-dependent Cdk2 activation and
p27 elimination. Quiescent FRTL-5 cells were incubated in 6H
medium for 36 h with or without 60 µg/ml of C3 exoenzyme plus
the other noted additions. Cell lysates (30 µg) were analyzed by
immunoblotting with antibodies against Cdk2 and p27 as described in the
text: lane 1, 4H; lane 2, 6H; lane 3,
6H + pravastatin; lane 4, 6H + pravastatin + GGPP; lane 5, C3 exoenzyme with 6H + pravastatin + GGPP.
[View Larger Version of this Image (22K GIF file)]
§
To whom correspondence should be addressed: The Second Dept. of
Internal Medicine, Chiba University Medical School, 1-8-1, Inohana-cho,
Chuou-ku, Chiba 260, Japan. Tel.: 81-43-226-2094; Fax: 81-43-226-2095;
E-mail: aizan{at}med.m.chiba-u.ac.jp.
1
The abbreviations used as are: Cdk2,
cyclin-dependent kinase 2; HMG-CoA,
3-hydroxy-3-methylglutaryl coenzyme A; TSH, thyrotropin; GGPP,
geranylgeranyl pyrophosphate; FPP, farnesyl pyrophosphate; IPP,
isopentenyl pyrophosphate; GST, glutathione
S-transferase.
©1997 by The American Society for Biochemistry and Molecular Biology, Inc.
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 A. Lukaszewicz, P. Savatier, V. Cortay, H. Kennedy, and C. Dehay Contrasting Effects of Basic Fibroblast Growth Factor and Neurotrophin 3 on Cell Cycle Kinetics of Mouse Cortical Stem Cells J. Neurosci., August 1, 2002; 22(15): 6610 - 6622. [Abstract] [Full Text] [PDF]
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W. Bao, M. Thullberg, H. Zhang, A. Onischenko, and S. Stromblad Cell Attachment to the Extracellular Matrix Induces Proteasomal Degradation of p21CIP1 via Cdc42/Rac1 Signaling Mol. Cell. Biol., July 1, 2002; 22(13): 4587 - 4597. [Abstract] [Full Text] [PDF]
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 B. Agarwal, B. Halmos, A. S. Feoktistov, P. Protiva, W. G. Ramey, M. Chen, C. Pothoulakis, J.T. Lamont, and P. R. Holt Mechanism of lovastatin-induced apoptosis in intestinal epithelial cells Carcinogenesis, March 1, 2002; 23(3): 521 - 528. [Abstract] [Full Text] [PDF]
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K. Yoshida, K. Nakayama, H. Nagahama, T. Harada, C. Harada, J. Imaki, A. Matsuda, K. Yamamoto, M. Ito, S. Ohno, et al. Involvement of p27KIP1 Degradation by Skp2 in the Regulation of Proliferation in Response to Wounding of Corneal Epithelium Invest. Ophthalmol. Vis. Sci., February 1, 2002; 43(2): 364 - 370. [Abstract] [Full Text] [PDF]
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D. L. Medina, M. Rivas, P. Cruz, I. Barroso, J. Regadera, and P. Santisteban RhoA Activation Promotes Transformation and Loss of Thyroid Cell Differentiation Interfering with Thyroid Transcription Factor-1 Activity Mol. Endocrinol., January 1, 2002; 16(1): 33 - 44. [Abstract] [Full Text] [PDF]
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 T. Kimura, A. Van Keymeulen, J. Golstein, A. Fusco, J. E. Dumont, and P. P. Roger Regulation of Thyroid Cell Proliferation by TSH and Other Factors: A Critical Evaluation of in Vitro Models Endocr. Rev., October 1, 2001; 22(5): 631 - 656. [Abstract] [Full Text] [PDF]
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 J. Sun, S. O. Marx, H.-J. Chen, M. Poon, A. R. Marks, and L. E. Rabbani Role for p27Kip1 in Vascular Smooth Muscle Cell Migration Circulation, June 19, 2001; 103(24): 2967 - 2972. [Abstract] [Full Text] [PDF]
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A. Van Keymeulen, S. Deleu, J. Bartek, J. E. Dumont, and P. P. Roger Respective Roles of Carbamylcholine and Cyclic Adenosine Monophosphate in Their Synergistic Regulation of Cell Cycle in Thyroid Primary Cultures Endocrinology, March 1, 2001; 142(3): 1251 - 1259. [Abstract] [Full Text] [PDF]
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 E. H.J. Danen, P. Sonneveld, A. Sonnenberg, and K. M. Yamada Dual Stimulation of Ras/Mitogen-activated Protein Kinase and RhoA by Cell Adhesion to Fibronectin Supports Growth Factor-stimulated Cell Cycle Progression J. Cell Biol., December 18, 2000; 151(7): 1413 - 1422. [Abstract] [Full Text] [PDF]
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 Z. Yang, T. Kozai, B. van de Loo, H. Viswambharan, M. Lachat, M. I. Turina, T. Malinski, and T. F. Luscher HMG-CoA reductase inhibition improves endothelial cell function and inhibits smooth muscle cell proliferation in human saphenous veins J. Am. Coll. Cardiol., November 1, 2000; 36(5): 1691 - 1697. [Abstract] [Full Text] [PDF]
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 J.-S. Park, L. Qiao, D. Gilfor, M. Y. Yang, P. B. Hylemon, C. Benz, G. Darlington, G. Firestone, P. B. Fisher, and P. Dent A Role for Both Ets and C/EBP Transcription Factors and mRNA Stabilization in the MAPK-dependent Increase in p21 Cip-1/WAF1/mda6 Protein Levels in Primary Hepatocytes Mol. Biol. Cell, September 1, 2000; 11(9): 2915 - 2932. [Abstract] [Full Text]
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C. J. Jones, D. Kipling, M. Morris, P. Hepburn, J. Skinner, A. Bounacer, F. S. Wyllie, M. Ivan, J. Bartek, D. Wynford-Thomas, et al. Evidence for a Telomere-Independent "Clock" Limiting RAS Oncogene-Driven Proliferation of Human Thyroid Epithelial Cells Mol. Cell. Biol., August 1, 2000; 20(15): 5690 - 5699. [Abstract] [Full Text]
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