Advertisement

Functional Cooperation among Ras, STAT5, and Phosphatidylinositol 3-Kinase Is Required for Full Oncogenic Activities of BCR/ABL in K562 Cells*

Open AccessPublished:January 04, 2002DOI:https://doi.org/10.1074/jbc.M111501200
      BCR/ABL tyrosine kinase generated from the chromosomal translocation t(9;22) causes chronic myelogenous leukemia and acute lymphoblastic leukemia. To examine the roles of BCR/ABL-activated individual signaling molecules and their cooperation in leukemogenesis, we inducibly expressed a dominant negative (DN) form of Ras, phosphatidylinositol 3-kinase, and STAT5 alone or in combination in p210 BCR/ABL-positive K562 cells. The inducibly expressed DN Ras (N17), STAT5 (694F), and DN phosphatidylinositol 3-kinase (Δp85) inhibited the growth by 90, 55, and 40%, respectively. During the growth inhibition, the expression of cyclin D2 and cyclin D3 was suppressed by N17, 694F, or Δp85; that of cyclin E by N17; and that of cyclin A by Δp85. In addition, N17 induced apoptosis in a small proportion of K562, whereas 694F and Δp85 were hardly effective. In contrast, coexpression of two DN mutants in any combinations induced severe apoptosis. During these cultures, the expression of Bcl-2 was suppressed by N17, 694F, or Δp85, and that of Bcl-XL by N17. Furthermore, although K562 was resistant to interferon-α- and dexamethasone-induced apoptosis, disruption of one pathway by N17, 694F, or Δp85 sensitized K562 to these reagents. These results suggested that cooperation among these molecules is required for full leukemogenic activities of BCR/ABL.
      CML
      chronic myelogenous leukemia
      MAPK
      mitogen-activated protein kinase
      STAT
      signal transducers and activators of transcription
      PI3-K
      phosphatidylinositol 3-kinase
      LacR
      Lac repressor
      Ab
      antibody
      IPTG
      isopropyl-β-d-thiogalactopyranoside
      TUNEL
      terminal deoxynucleotidyltransferase-mediated biotin-dUTP nick end labeling
      BCR
      breakpoint cluster region
      ALL
      acute lymphoblastic leukemia
      IFN
      interferon
      DN
      dominant negative
      PI
      propidium iodide
      NF-κB
      nuclear factor κB
      PBS
      phosphate-buffered saline
      CDK
      cyclin-dependent kinase
      Chronic myelogenous leukemia (CML)1 is a malignant clonal disorder of hematopoietic stem/progenitor cells (as reviewed in Refs.
      • Sawyers C.L.
      ,
      • Sattler M.
      • Griffin J.D.
      ,
      • Maru Y.
      ). The diagnostic hallmark of CML is the Philadelphia chromosome, the derivative chromosome 22 resulting from the reciprocal chromosomal translocation t(9:22)(q34;q11), which is observed in over 90% of patients with CML. This translocation joins c-Abl tyrosine kinase on chromosome 9 and breakpoint cluster region (BCR) on chromosome 22, leading to the generation of the fusion gene for BCR/ABL. According to the difference in the breakpoint in BCR, three types of BCR/ABL fusion proteins, p210, p190, and p230, are generated. p210 BCR/ABL was observed in ∼90% of CML patients and in a small fraction of acute lymphoblastic leukemia (ALL) patients, whereas p190 BCR/ABL and p230 BCR/ABL are associated with ALL and chronic neutrophilic leukemia, respectively. However, it still remains unknown how these three forms of BCR/ABL differ from each other in terms of their downstream signaling or induce distinct diseases. c-Abl tyrosine kinase exists in both cytoplasm and nucleus and induces apoptosis in response to DNA damage through the cooperation with the p53 homologue, p73, whereas BCR/ABL primarily localizes to cytoplasm and acts as an oncogene (for a review, see Ref.
      • Wang J.Y.
      ). This cytoplasmic localization of BCR/ABL is essential for its biologic activities because BCR/ABL entrapped into the nucleus by leptomycin B induces apoptosis with its tyrosine kinase activities (
      • Vigneri P.
      • Wang J.Y.
      ).
      As for the biologic activities of BCR/ABL in oncogenesis, a number ofin vitro experiments have shown that BCR/ABL enabled primitive hematopoietic cells as well as factor-dependent hematopoietic cell lines such as Ba/F3, 32D, and FDC-P1 to proliferate under factor-deprived conditions (
      • Gishizky M.L.
      • Witte O.N.
      ,
      • Daley G.Q.
      • Baltimore D.
      ,
      • Hariharan I.K.
      • Adams J.M.
      • Cory S.
      ,
      • Laneuville P.
      • Heisterkamp N.
      • Groffen J.
      ). In addition, enforced expression of p210 or p190 BCR/ABL in Rat-1 fibroblasts caused a distinct morphologic change and conferred both tumorigenicity and capacity for anchorage-independent growth (
      • Lugo T.G.
      • Witte O.N.
      ). Furthermore, when bone marrow cells infected with retrovirus expressing p210 BCR/ABL were transplanted into lethally irradiated mice, some of the recipients developed various types of hematologic malignancies including granulocytic hyperplasia resembling human CML, myelomonocytic leukemia, ALL, lymphomas, and erythroid leukemia (
      • Daley G.Q.
      • Van Etten R.A.
      • Baltimore D.
      ,
      • Elefanty A.G.
      • Hariharan I.K.
      • Cory S.
      ,
      • Kelliher M.A.
      • McLaughlin J.
      • Witte O.N.
      • Rosenberg N.
      ). Moreover, transgenic mice expressing p210 BCR/ABL developed pre-B or T cell lymphomas, T-ALL, or myeloproliferative disorder like CML (
      • Hariharan I.K.
      • Harris A.W.
      • Crawford M.
      • Abud H.
      • Webb E.
      • Cory S.
      • Adams J.M.
      ,
      • Honda H.
      • Fujii T.
      • Takatoku M.
      • Mano H.
      • Witte O.N.
      • Yazaki Y.
      • Hirai H
      ,
      • Honda H.
      • Oda H.
      • Suzuki T.
      • Takahashi T.
      • Witte O.N.
      • Ozawa K.
      • Ishikawa T.
      • Yazaki Y.
      • Hirai H.
      ). These results indicated that BCR/ABL indeed acts as an oncogene and causes hematologic malignancies in vivo.
      Growth and survival of hematopoietic cells are regulated by a number of hematopoietic growth factors. Upon the stimulation with the ligand, receptors for hematopoietic growth factors transmit mitogenic and anti-apoptotic signals through activation of their downstream molecules. To keep homeostasis of hematopoiesis, these cytokine signals are subsequently eliminated by negative feedback mechanisms including ubiquitin/proteasome-dependent protein degradation, activation of phosphatases, and induction of inhibitory molecules. By contrast, activated mutants of the upper stream signaling molecule such as TEL/platelet-derived growth factor receptor, tandem duplication of FLT3, activating point mutation of c-kit, and TEL/JAK2 cause excessive growth, survival, and consequent malignant transformation of hematopoietic cells through constitutive activation of downstream cascades. In addition to these oncogenic signaling molecules, the BCR/ABL tyrosine kinase also activates various signaling molecules including the Ras/mitogen-activated protein kinase (MAPK) pathway, the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway, and signal transducers and activators of transcription (STATs, STAT1 and STAT5), and acts as an oncogene (as reviewed in Ref.
      • Odajima J.
      • Matsumura I.
      • Sonoyama J.
      • Daino H.
      • Kawasaki A.
      • Tanaka H.
      • Inohara N.
      • Kitamura T.
      • Downward J.
      • Nakajima K.
      • Hirano T.
      • Kanakura Y.
      ). As for the roles of these signaling molecules in BCR/ABL-mediated leukemogenesis, a dominant negative (DN) form of Ras inhibited the growth and survival of BCR/ABL-transformed 32D cells (
      • Cortez D.
      • Stoica G.
      • Pierce J.H.
      • Pendergast A.M.
      ). Similarly, DN STAT5 suppressed apoptosis resistance, factor-independent proliferation, and leukemogenic potential of a CML-derived cell line, K562, and BCR/ABL-transformed 32D and Ba/F3 (
      • Nieborowska-Skorska M.
      • Wasik M.A.
      • Slupianek A.
      • Salomoni P.
      • Kitamura T.
      • Calabretta B.
      • Skorski T.
      ,
      • de Groot R.P.
      • Raaijmakers J.A.
      • Lammers J.W.
      • Jove R.
      • Koenderman L.
      ,
      • Sillaber C.
      • Gesbert F.
      • Frank D.A.
      • Sattler M.
      • Griffin J.D.
      ). In addition, a mutant form of BCR/ABL that cannot activate PI3-K did not confer leukemogenic potentials on murine bone marrow cells in vitroand in vivo, indicating that PI3-K/Akt pathway is also required for BCR/ABL-induced malignant transformation of hematopoietic cells (
      • Skorski T.
      • Bellacosa A.
      • Nieborowska-Skorska M.
      • Majewski M.
      • Martinez R.
      • Choi J.K.
      • Trotta R.
      • Wlodarski P.
      • Perrotti D.
      • Chan T.O.
      • Wasik M.A.
      • Tsichlis P.N.
      • Calabretta B.
      ). Together, these results indicated that Ras, STAT5, and PI3-K can each play essential roles in BCR/ABL-mediated leukemogenesis. However, the precise mechanisms by which each signaling molecule mediates BCR/ABL-dependent growth and survival are unknown. Additionally, the functional relationship among these signaling cascades remains to be clarified.
      Therefore, in this study, we examined the functions of Ras, STAT5, and PI3-K by expressing respective DN mutant alone or in combination in p210 BCR/ABL-positive CML-derived cell line, K562. Our experiments demonstrated that Ras, STAT5, and PI3-K individually participate in BCR/ABL-dependent growth and survival of K562, whereas Ras seemed to play a central role among these molecules. Regarding this mechanism, we found that cooperation among these signaling pathways is required for maintaining the expressions of critical molecules for cell cycle progression or cell survival such as cyclin D2, cyclin D3, and Bcl-2. In addition, disruption of only one signaling pathway (Ras, STAT5, or PI3-K) made K562 cells susceptible to interferon-α (IFN-α)- or dexamethasone-induced apoptosis. These results suggested simultaneous activation of multiple signaling pathways is necessary for full leukemogenic activities of BCR/ABL and that new therapeutic strategies to abrogate at least one signaling pathway might enhance the efficacy of conventional reagents in therapy-resistant CML patients.

      DISCUSSION

      During the last decade, a number of studies have been made to clarify the mechanisms how signaling molecules activated by cytokines or oncogenes regulate the functions and expressions of cell cycle regulatory molecules. Ras was shown to up-regulate the expressions of cyclin D1 and c-myc, to down-regulate the protein expression level of cyclin-dependent kinase (CDK) inhibitor p27Kip1, and to activate cdc25 phosphatases, thereby inducing cell cycle progression from G1 to S phase (for a review, see Ref.
      • Kerkhoff E.
      • Rapp U.R.
      ). In addition, Ras activities influence cell cycle machinery at several phases. Meanwhile, STAT5 was reported to mediate the growth of hematopoietic cells through inducing cyclin D1 and pim-1 (
      • Matsumura I.
      • Kitamura T.
      • Wakao H.
      • Tanaka H.
      • Hashimoto K.
      • Albanese C.
      • Downward J.
      • Pestell R.G.
      • Kanakura Y.
      ,
      • Nosaka T.
      • Kawashima T.
      • Misawa K.
      • Ikuta K.
      • Mui A.L.
      • Kitamura T.
      ). PI3-K/Akt was also assumed to promote cell cycle progression through induction of cyclin D3, stabilization of cyclin D1, degradation of p27Kip1 and phosphorylation of p21WAF1(
      • Diehl J.A.
      • Cheng M.
      • Roussel M.F.
      • Sherr C.J.
      ,
      • Rossig L.
      • Jadidi A.S.
      • Urbich C.
      • Badorff C.
      • Zeiher A.M.
      • Dimmeler S.
      ,
      • Brennan P.
      • Babbage J.W.
      • Burgering B.M.
      • Groner B.
      • Reif K.
      • Cantrell D.A.
      ,
      • Zhou B.P.
      • Liao Y.
      • Xia W.
      • Spohn B.
      • Lee M.H.
      • Hung M.C.
      ). These studies indicated that Ras, STAT5, and PI3-K can individually promote cell cycle progression from G1 to S phase. In accord with these results, we found here that Ras, STAT5, and PI3-K each contribute to BCR/ABL-dependent cell growth, although Ras seemed to play the most important role among these molecules. Although Ras and STAT5 have been reported to induce cyclin D1 expression (
      • Matsumura I.
      • Kitamura T.
      • Wakao H.
      • Tanaka H.
      • Hashimoto K.
      • Albanese C.
      • Downward J.
      • Pestell R.G.
      • Kanakura Y.
      ,
      • Kerkhoff E.
      • Rapp U.R.
      ,
      • de Groot R.P.
      • Raaijmakers J.A.
      • Lammers J.W.
      • Koenderman L.
      ), we could not detect any cyclin D1 expression in K562. Therefore, cyclin D2, cyclin D3, and cyclin E were supposed to regulate CDK activities required for G1/S progression (i.e. activities of CDK4, CDK6, and CDK2) instead of cyclin D1 in K562. Under these circumstances, the expressions of cyclin D2 and cyclin D3 were inhibited by either N17, 694F, or Δp85. These results suggested that the functional role of each signal is not redundant but indispensable for the expressions of cyclin D2 and cyclin D3. Furthermore, as the expression of cyclin E and that of cyclin A, which regulates G2/M phase, were specifically inhibited by N17 and Δp85, respectively, each signaling molecule was supposed to individually contribute to BCR/ABL-dependent growth through the induction of their unique target gene(s).
      Excessive cell cycle progression lacking anti-apoptotic signals has been shown to result in aggressive cell death (as reviewed in Refs.
      • Prendergast G.C.
      and
      • Harbour J.W.
      • Dean D.C.
      ). Therefore, most oncogenic signaling molecules transmit both anti-apoptotic signals and mitogenic signals to their downstream cascades simultaneously. Among these molecules, Ras mediates anti-apoptotic signals, at least in part, by activation of PI3-K (
      • Rodriguez-Viciana P.
      • Warne P.H.
      • Dhand R.
      • Vanhaesebroeck B.
      • Gout I.
      • Fry M.J.
      • Waterfield MD.
      • Downward J.
      ), although we did not detect this relationship in K562. In addition, Ras induces the expressions of anti-apoptotic molecules, Bcl-2 and Bcl-XL (
      • Kinoshita T.
      • Yokota T.
      • Arai K.
      • Miyajima A.
      ). Similarly, STAT5 induces these expressions (
      • Socolovsky M.
      • Fallon A.E.
      • Wang S.
      • Brugnara C.
      • Lodish H.F.
      ,
      • Lord J.D.
      • McIntosh B.C.
      • Greenberg P.D.
      • Nelson B.H.
      ). Meanwhile, PI3-K/Akt exerts anti-apoptotic effects by inhibiting the function of pro-apoptotic molecules, BAD, FKHRL1 (by phosphorylation), and caspases (by degradation) (as reviewed in Ref.
      • Datta S.R.
      • Brunet A.
      • Greenberg M.E.
      ). In agreement with these anti-apoptotic roles of signaling molecules, BCR/ABL was found to induce expressions of Bcl-2 and Bcl-XL and phosphorylation of Bad in host cells probably through the activation of Ras, STAT5, and PI3-K (
      • de Groot R.P.
      • Raaijmakers J.A.
      • Lammers J.W.
      • Koenderman L.
      ,
      • Neshat M.S.
      • Raitano A.B.
      • Wang H.G.
      • Reed J.C.
      • Sawyers C.L.
      ,
      • Horita M.
      • Andreu E.J.
      • Benito A.
      • Arbona C.
      • Sanz C.
      • Benet I.
      • Prosper F.
      • Fernandez-Luna J.L.
      ,
      • Gesbert F.
      • Griffin J.D.
      ,
      • Sanchez-Garcia I.
      • Grutz G.
      ). In the present study, BCR/ABL-mediated Bcl-2 expression was disrupted by each of N17, 694F, and Δp85, implying that cooperation among three signaling molecules was required for maintaining its expression. In addition, when two DN mutants were coexpressed, K562 underwent severe apoptosis, suggesting that the remaining one pathway, i.e. Ras, STAT5, or PI3-K alone, was not able to support the growth or survival of K562. However, because both oncogenic Ras (Ha-RasG12V) and constitutively active STAT5 (1*6-STAT5) were shown to induce Bcl-2 expression and enabled factor-dependent Ba/F3 cells to proliferate under factor-deprived conditions (
      • Odajima J.
      • Matsumura I.
      • Sonoyama J.
      • Daino H.
      • Kawasaki A.
      • Tanaka H.
      • Inohara N.
      • Kitamura T.
      • Downward J.
      • Nakajima K.
      • Hirano T.
      • Kanakura Y.
      ,
      • Nosaka T.
      • Kawashima T.
      • Misawa K.
      • Ikuta K.
      • Mui A.L.
      • Kitamura T.
      ), it was possible that BCR/ABL may not activate Ras, STAT5, or PI3-K to the full extent in K562 and possibly in CML cells, and that, for this reason, the simultaneous activation of multiple signaling cascades was necessary for leukemogenic activities of BCR/ABL.
      Although the induced expression of N17 alone was sufficient for suppressing Bcl-2 and Bcl-XL expressions, N17 was less effective in inducing apoptosis than N17+694F or N17+Δp85. In addition, 694F+Δp85 induced apoptosis as efficiently as N17+694F or N17+Δp85, whereas Bcl-XL expression was maintained in this clone (data not shown). Together, these data raised a possibility that an additional anti-apoptotic molecule(s) other than Bcl-2 and Bcl-XL, which would be regulated by Ras, STAT5, and/or PI3-K, might also control BCR/ABL- dependent cell survival. Among several candidate molecules, NF-κB seemed to be most likely because NF-κB was reported to be activated by BCR/ABL and to be involved in the resistance to drug-induced apoptosis in K562 (
      • Lu Y.
      • Jamieson L.
      • Brasier A.R.
      • Fields A.P.
      ,
      • Reuther J.Y.
      • Reuther G.W.
      • Cortez D.
      • Pendergast A.M.
      • Baldwin Jr., A.S.
      ).
      K562 was shown to be resistant to apoptosis induced by actinomycin D, camptothecin, etoposide, and cycloheximide as well as Fas-induced apoptosis (
      • McGahon A.
      • Bissonnette R.
      • Schmitt M.
      • Cotter K.M.
      • Green D.R.
      • Cotter T.G.
      ,
      • McGahon A.J.
      • Nishioka W.K.
      • Martin S.J.
      • Mahboubi A.
      • Cotter T.G.
      • Green D.R.
      ). Regarding this mechanism, it has been reported that BCR/ABL-mediated expression of Bcl-XL, activities of protein kinase Ciota, and VLA-5-mediated cell adhesion were involved in these drug-resistance (
      • Lu Y.
      • Jamieson L.
      • Brasier A.R.
      • Fields A.P.
      ,
      • van der Kuip H.
      • Goetz A.W.
      • Miething C.
      • Duyster J.
      • Aulitzky W.E.
      ,
      • Damiano J.S.
      • Hazlehurst L.A.
      • Dalton W.S.
      ,
      • Laroche-Clary A.
      • Larrue A.
      • Robert J.
      ). In addition, Sluplanek et al. (
      • Slupianek A.
      • Schmutte C.
      • Tombline G.
      • Nieborowska-Skorska M.
      • Hoser G.
      • Nowicki M.O.
      • Pierce A.J.
      • Fishel R.
      • Skorski T.
      ) recently demonstrated that STAT5-induced RAD51, a mammalian homologue of the E. coli RecA protein was essentially important for resistance to cisplatin and mitomycin C. In addition, we found here that disruption of one signaling cascade by N17, 694F, or Δp85 equally sensitized K562 to IFN-α- or dexamethasone-induced apoptosis. Because Bcl-2 expression was down-regulated in these clones, Bcl-2 was also supposed to play some role in BCR/ABL-mediated drug-resistance.
      In summary, we showed here that Ras, STAT5, and PI3-K pathways cooperatively contribute to BCR/ABL-dependent cell growth and survival in K562 cells. Although STI571 has been shown to be practically effective in a considerable proportion of CML patients, many patients in advanced stage become refractory to this drug as a result of reactivation of BCR/ABL signal transduction (
      • Druker B.J.
      • Talpaz M.
      • Resta D.J.
      • Peng B.
      • Buchdunger E.
      • Ford J.M.
      • Lydon N.B.
      • Kantarjian H.
      • Capdeville R.
      • Ohno-Jones S.
      • Sawyers C.L.
      ,
      • Gorre M.E.
      • Mohammed M.
      • Ellwood K.
      • Hsu N.
      • Paquette R.
      • Rao P.N.
      • Sawyers C.L.
      ). Thus, further studies to elucidate the functional network among these signaling molecules would provide more useful information to design new therapeutic strategies that target these molecules and to overcome the drug resistance.

      Acknowledgments

      We thank Drs. A. Arnold, G. Peters, H. Kiyokawa, E. Harlow, Y. Tsujimoto, and T. Tsujimura for providing the plasmids.

      REFERENCES

        • Sawyers C.L.
        N. Engl. J. Med. 1999; 340: 1330-1340
        • Sattler M.
        • Griffin J.D.
        Int. J. Hematol. 2001; 73: 278-291
        • Maru Y.
        Int. J. Hematol. 2001; 73: 308-322
        • Wang J.Y.
        Oncogene. 2000; 19: 5643-5650
        • Vigneri P.
        • Wang J.Y.
        Nat. Med. 2001; 7: 228-234
        • Gishizky M.L.
        • Witte O.N.
        Science. 1992; 256: 836-839
        • Daley G.Q.
        • Baltimore D.
        Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 9312-9316
        • Hariharan I.K.
        • Adams J.M.
        • Cory S.
        Oncogene Res. 1988; : 387-399
        • Laneuville P.
        • Heisterkamp N.
        • Groffen J.
        Oncogene. 1991; 6: 275-282
        • Lugo T.G.
        • Witte O.N.
        Mol. Cell. Biol. 1989; 9: 1263-1270
        • Daley G.Q.
        • Van Etten R.A.
        • Baltimore D.
        Science. 1990; 247: 824-830
        • Elefanty A.G.
        • Hariharan I.K.
        • Cory S.
        EMBO J. 1990; 9: 1069-1078
        • Kelliher M.A.
        • McLaughlin J.
        • Witte O.N.
        • Rosenberg N.
        Proc. Natl. Acad. Sci. U. S. A. 1990; 87: 6649-6653
        • Hariharan I.K.
        • Harris A.W.
        • Crawford M.
        • Abud H.
        • Webb E.
        • Cory S.
        • Adams J.M.
        Mol. Cell. Biol. 1989; 9: 2798-2805
        • Honda H.
        • Fujii T.
        • Takatoku M.
        • Mano H.
        • Witte O.N.
        • Yazaki Y.
        • Hirai H
        Blood. 1995; 85: 2853-2861
        • Honda H.
        • Oda H.
        • Suzuki T.
        • Takahashi T.
        • Witte O.N.
        • Ozawa K.
        • Ishikawa T.
        • Yazaki Y.
        • Hirai H.
        Blood. 1998; 91: 2067-2075
        • Cortez D.
        • Stoica G.
        • Pierce J.H.
        • Pendergast A.M.
        Oncogene. 1996; 13: 2589-2594
        • Nieborowska-Skorska M.
        • Wasik M.A.
        • Slupianek A.
        • Salomoni P.
        • Kitamura T.
        • Calabretta B.
        • Skorski T.
        J. Exp. Med. 1999; 189: 1229-1242
        • de Groot R.P.
        • Raaijmakers J.A.
        • Lammers J.W.
        • Jove R.
        • Koenderman L.
        Blood. 1999; 94: 1108-1112
        • Sillaber C.
        • Gesbert F.
        • Frank D.A.
        • Sattler M.
        • Griffin J.D.
        Blood. 2000; 95: 2118-2125
        • Skorski T.
        • Bellacosa A.
        • Nieborowska-Skorska M.
        • Majewski M.
        • Martinez R.
        • Choi J.K.
        • Trotta R.
        • Wlodarski P.
        • Perrotti D.
        • Chan T.O.
        • Wasik M.A.
        • Tsichlis P.N.
        • Calabretta B.
        EMBO J. 1997; 16: 6151-6161
        • Matsumura I.
        • Nakajima K.
        • Wakao H.
        • Hattori S.
        • Hashimoto K.
        • Sugahara H.
        • Kato T.
        • Miyazaki H.
        • Hirano T.
        • Kanakura Y.
        Mol. Cell. Biol. 1998; 18: 4282-4290
        • Odajima J.
        • Matsumura I.
        • Sonoyama J.
        • Daino H.
        • Kawasaki A.
        • Tanaka H.
        • Inohara N.
        • Kitamura T.
        • Downward J.
        • Nakajima K.
        • Hirano T.
        • Kanakura Y.
        J. Biol. Chem. 2000; 275: 24096-24105
        • Matsumura I.
        • Kitamura T.
        • Wakao H.
        • Tanaka H.
        • Hashimoto K.
        • Albanese C.
        • Downward J.
        • Pestell R.G.
        • Kanakura Y.
        EMBO J. 1999; 18: 1367-1377
        • Matsumura I.
        • Kawasaki A.
        • Tanaka H.
        • Sonoyama J.
        • Ezoe S.
        • Minegishi N.
        • Nakajima K.
        • Yamamoto M.
        • Kanakura Y.
        Blood. 2000; 96: 2440-2450
        • Rodriguez-Viciana P.
        • Warne P.H.
        • Dhand R.
        • Vanhaesebroeck B.
        • Gout I.
        • Fry M.J.
        • Waterfield MD.
        • Downward J.
        Nature. 1994; 370: 527-532
        • Chida D.
        • Wakao H.
        • Yoshimura A.
        • Miyajima A.
        Mol. Endocrinol. 1998; 12: 1792-1806
        • Kerkhoff E.
        • Rapp U.R.
        Oncogene. 1998; 17: 1457-1462
        • Nosaka T.
        • Kawashima T.
        • Misawa K.
        • Ikuta K.
        • Mui A.L.
        • Kitamura T.
        EMBO J. 1999; 18: 4754-4765
        • Diehl J.A.
        • Cheng M.
        • Roussel M.F.
        • Sherr C.J.
        Genes Dev. 1998; 12: 3499-3511
        • Rossig L.
        • Jadidi A.S.
        • Urbich C.
        • Badorff C.
        • Zeiher A.M.
        • Dimmeler S.
        Mol. Cell. Biol. 2001; 21: 5644-5657
        • Brennan P.
        • Babbage J.W.
        • Burgering B.M.
        • Groner B.
        • Reif K.
        • Cantrell D.A.
        Immunity. 1997; 7: 679-689
        • Zhou B.P.
        • Liao Y.
        • Xia W.
        • Spohn B.
        • Lee M.H.
        • Hung M.C.
        Nat. Cell Biol. 2001; 3: 245-252
        • de Groot R.P.
        • Raaijmakers J.A.
        • Lammers J.W.
        • Koenderman L.
        Mol. Cell. Biol. Res. Commun. 2000; 3: 299-305
        • Prendergast G.C.
        Oncogene. 1999; 18: 2967-2987
        • Harbour J.W.
        • Dean D.C.
        Genes Dev. 2000; 14: 2393-2409
        • Kinoshita T.
        • Yokota T.
        • Arai K.
        • Miyajima A.
        Oncogene. 1995; 10: 2207-2212
        • Socolovsky M.
        • Fallon A.E.
        • Wang S.
        • Brugnara C.
        • Lodish H.F.
        Cell. 1999; 98: 181-191
        • Lord J.D.
        • McIntosh B.C.
        • Greenberg P.D.
        • Nelson B.H.
        J. Immunol. 2000; 164: 2533-2541
        • Datta S.R.
        • Brunet A.
        • Greenberg M.E.
        Genes Dev. 1999; 13: 2905-2927
        • Neshat M.S.
        • Raitano A.B.
        • Wang H.G.
        • Reed J.C.
        • Sawyers C.L.
        Mol. Cell. Biol. 2000; 20: 1179-1186
        • Horita M.
        • Andreu E.J.
        • Benito A.
        • Arbona C.
        • Sanz C.
        • Benet I.
        • Prosper F.
        • Fernandez-Luna J.L.
        J. Exp. Med. 2000; 191: 977-984
        • Gesbert F.
        • Griffin J.D.
        Blood. 2000; 96: 2269-2276
        • Sanchez-Garcia I.
        • Grutz G.
        Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 5287-5291
        • Lu Y.
        • Jamieson L.
        • Brasier A.R.
        • Fields A.P.
        Oncogene. 2001; 20: 4777-4792
        • Reuther J.Y.
        • Reuther G.W.
        • Cortez D.
        • Pendergast A.M.
        • Baldwin Jr., A.S.
        Genes Dev. 1998; 12: 968-981
        • McGahon A.
        • Bissonnette R.
        • Schmitt M.
        • Cotter K.M.
        • Green D.R.
        • Cotter T.G.
        Blood. 1994; 83: 1179-1187
        • McGahon A.J.
        • Nishioka W.K.
        • Martin S.J.
        • Mahboubi A.
        • Cotter T.G.
        • Green D.R.
        J. Biol. Chem. 1995; 270: 22625-22631
        • van der Kuip H.
        • Goetz A.W.
        • Miething C.
        • Duyster J.
        • Aulitzky W.E.
        Blood. 2001; 98: 1532-1541
        • Damiano J.S.
        • Hazlehurst L.A.
        • Dalton W.S.
        Leukemia. 2001; 15: 1232-1239
        • Laroche-Clary A.
        • Larrue A.
        • Robert J.
        Biochem. Pharmacol. 2000; 60: 1823-1828
        • Slupianek A.
        • Schmutte C.
        • Tombline G.
        • Nieborowska-Skorska M.
        • Hoser G.
        • Nowicki M.O.
        • Pierce A.J.
        • Fishel R.
        • Skorski T.
        Mol. Cell. 2001; 8: 795-806
        • Druker B.J.
        • Talpaz M.
        • Resta D.J.
        • Peng B.
        • Buchdunger E.
        • Ford J.M.
        • Lydon N.B.
        • Kantarjian H.
        • Capdeville R.
        • Ohno-Jones S.
        • Sawyers C.L.
        N. Engl. J. Med. 2001; 344: 1031-1037
        • Gorre M.E.
        • Mohammed M.
        • Ellwood K.
        • Hsu N.
        • Paquette R.
        • Rao P.N.
        • Sawyers C.L.
        Science. 2001; 293: 876-880