ACCELERATED PUBLICATION
The ARG Tyrosine Kinase Interacts with Siva-1 in the Apoptotic Response to Oxidative Stress*

Cheng Cao, Xinping Ren, Surender Kharbanda, Anthony KoleskeDagger , K. V. S. Prasad§, and Donald Kufe||

Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115 and Dagger  Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, and § Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois 60612

Received for publication, January 30, 2001



    ABSTRACT
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES

The Abl family of mammalian nonreceptor tyrosine kinases consists of c-Abl and ARG (Abl-related gene). Certain insights are available regarding the involvement c-Abl in the response of cells to stress. ARG, however, has no known function in cell signaling. The present studies demonstrate that ARG associates with the proapoptotic Siva-1 protein. The functional significance of the ARG-Siva-1 interaction is supported by the finding that ARG is activated by oxidative stress and that this response involves ARG-mediated phosphorylation of Siva-1 on Tyr48. The proapoptotic effects of Siva-1 are accentuated in cells stably expressing ARG and are inhibited in ARG-deficient cells. Moreover, the proapoptotic effects of Siva-1 are abrogated by mutation of the Tyr48 site. We also show that the apoptotic response to oxidative stress is attenuated in ARG-deficient cells and that this defect is corrected by reconstituting ARG expression. These findings support a model in which the activation of ARG by oxidative stress induces apoptosis by a Siva-1-dependent mechanism.



    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES

The mammalian c-Abl and ARG1 nonreceptor tyrosine kinases are ubiquitously expressed in adult tissues (1, 2). These proteins contain N-terminal SH3, SH2, and kinase domains that share ~90% identity. The C-terminal regions of c-Abl and ARG share 29% identity and are distinguished from other nonreceptor tyrosine kinases by the presence of globular (G) and filamentous (F) actin-binding domains (3). The c-Abl protein is expressed in the nucleus and cytoplasm, whereas ARG has been detected predominately in the cytoplasm (4). In addition, the C-terminal region of c-Abl differs from ARG by the presence of a nuclear localization signal (5), sites for phosphorylation by the Cdc2 kinase (6), and DNA binding sequences (7). The structural differences of the C-terminal regions have suggested that c-Abl and ARG may share only certain cellular functions.

Mice with targeted disruption of the c-abl gene are born runted with head and eye abnormalities and succumb as neonates to defective lymphopoiesis (8, 9). Mice deficient in ARG develop normally but exhibit behavioral abnormalities (10). Embryos deficient in both c-Abl and ARG exhibit defects in neurolation and die before 11 days postcoitum (10). These findings and the observation that abl-/-, arg-/- neuroepithelial cells exhibit an altered actin cytoskeleton have supported roles for c-Abl and ARG in the regulation of actin microfilaments (10).

Other studies have demonstrated that c-Abl is involved in the cellular response to stress (11). Nuclear c-Abl associates with the DNA-dependent protein kinase (DNA-PK) complex (12, 13) and with the product of the gene mutated in ataxia telangiectasia (14, 15). Activation of c-Abl by DNA-PK and ataxia telangiectasia mutated gene product in cells exposed to genotoxic agents contributes to DNA damage-induced apoptosis by mechanisms in part dependent on p53 and its homolog p73 (11, 16-19). In the cellular response to reactive oxygen species (ROS), the cytoplasmic form of c-Abl is activated by protein kinase C delta  (PKCdelta ) (20). Activation of cytoplasmic c-Abl by ROS transduces signals that induce release of mitochondrial cytochrome c and thereby apoptosis (21).

No functional role has been ascribed to ARG as a cell signaling molecule. The present studies demonstrate that ARG interacts with the proapoptotic Siva-1 protein (22, 23). ARG phosphorylates Siva-1 in the cellular response to oxidative stress and induces apoptosis by a Siva-1-dependent mechanism.


    MATERIALS AND METHODS
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES

Cell Culture and Transfections-- 293, MCF-7, and mouse embryo fibroblasts (MEFs, wild-type, and arg-/-) were grown in Dulbecco's modified Eagle's medium supplemented with 10% heat-inactivated fetal bovine serum, 2 mM L-glutamine, 100 units/ml penicillin, and 100 µg/ml streptomycin. Transient transfections were performed with LipofectAMINE (Life Technologies, Inc.). MCF-7 cells stably expressing ARG or ARG(K-R) were established by selection in G418.

Vectors-- Flag-tagged ARG, ARG(K-R), and Siva-1 were constructed by cloning into the pcDNA3.1-based Flag vector. GFP-Siva constructs were obtained by cloning into pEGFPC1 (CLONTECH). Retrovirus-expressing Siva-1 was prepared by cloning the human siva-1 gene into the pLXSN vector (CLONTECH). The arg gene was cloned into the retroviral vector pMSCV-IRES-GFP.

Immunoprecipitation and Immunoblot Analysis-- Cell lysates were prepared in lysis buffer (50 mM Tris-HCl, pH 7.5, 1 mM phenylmethylsulfonyl fluoride, 1 mM dithiothreitol, 10 mM sodium fluoride, and 10 µg/ml aprotinin, leupeptin, and pepstatin A) containing 0.5% Nonidet P-40. Soluble protein was subjected to immunoprecipitation with anti-Flag (agarose-conjugated, M-2, Sigma). Immunoblot analysis was performed with anti-GFP (CLONTECH) and anti-ARG (rabbit antibody against ARG-specific C-terminal QVSSAAAGVPGTNPVLNNL peptide). The antigen-antibody complexes were visualized by chemiluminescence (ECL, Amersham Pharmacia Biotech).

Binding Assays-- Cell lysates were incubated with 5 µg of GST, GST-ARG SH2-(162-259), GST-ARG SH3-(112-161), or GST-Siva-1 for 2 h at 4 °C. The adsorbates were washed with lysis buffer and then subjected to immunoblotting with anti-Flag (M5, Sigma). An aliquot of the total lysate (2% v/v) was included as a control. For direct binding assays, purified GST fusion proteins were incubated with 15 µl of 35S-labeled Siva-1. The adsorbates were analyzed by SDS-PAGE and autoradiography. An aliquot (0.5 µl) of the 35S-labeled protein was loaded as input.

ARG Kinase Assays-- Lysates from Flag-ARG- or Flag-ARG(K-R)- transfected cells were subjected to immunoprecipitation with anti-Flag-agarose. The protein complexes were washed, normalized by immunoblot analysis with anti-Flag, and then resuspended in kinase buffer (20 mM HEPES, pH 7.5, 75 mM KCl, 10 mM MgCl2, 10 mM MnCl2) containing 2.5 µCi of [gamma -32P]ATP and 2 µg of GST-Siva-1 for 30 min at 30 °C. The reaction products were analyzed by SDS-PAGE and autoradiography.

Apoptosis Assays-- The DNA content was assessed by staining ethanol-fixed and citrate buffer-permeabilized cells with propidium iodide and monitoring by FACScan (Becton Dickinson). The numbers of cells with sub-G1 DNA were determined with a MODFIT LT program as described (24).


    RESULTS AND DISCUSSION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES

To extend the findings in the yeast two-hybrid system that ARG associates with the pro-apoptotic Siva-1 protein (data not shown), lysates from MCF-7 cells expressing Flag-tagged ARG and GFP-tagged human Siva-1 were subjected to immunoprecipitation with anti-Flag. Analysis of the precipitates by immunoblotting with anti-GFP demonstrated the presence of ARG-Siva-1 complexes (Fig. 1A, left). Analysis of anti-Flag immunoprecipitates from cells expressing Flag-Siva-1 by immunoblotting with anti-ARG provided further support for binding of ARG and Siva-1 (Fig. 1A, right). To extend these findings, lysates from cells expressing Flag-ARG were incubated with a GST-Siva-1 fusion protein. Analysis of the adsorbates with anti-Flag confirmed the binding of ARG and Siva-1 (Fig. 1B). Other studies with GST fusion proteins prepared from the ARG SH2 and ARG SH3 domains demonstrated that both confer binding to Siva-1 (Fig. 1C). By contrast, binding of GST-ARG SH2, but not GST-ARG SH3, was detectable to the shorter, nonapoptotic Siva-2 protein (Fig. 1D). Human Siva-1, but not Siva-2, contains a proline-rich PESP sequence (amino acids 82-85) for potential binding to ARG SH3. Notably, however, the PESP site is not conserved in mouse Siva-1 (22, 23). In this regard, GST-ARG SH2, and not GST-ARG SH3, binds to mouse Siva-1 (data not shown). These findings demonstrate that the ARG SH2 domain interacts with Siva-1 and Siva-2 of both human and mouse origin and that binding of the ARG SH3 domain is also detectable with human Siva-1.



View larger version (37K):
[in this window]
[in a new window]
 
Fig. 1.   Association of ARG and Siva-1. A, 293 cells were transfected with Flag-ARG and GFP-Siva-1. Lysates prepared at 48 h after transfection were subjected to immunoprecipitation (IP) with anti-Flag. The immunoprecipitates were analyzed by immunoblotting (IB) with anti-GFP (left panel). MCF-7 cells were transfected with the empty Flag vector or Flag-Siva-1. Anti-Flag immunoprecipitates were subjected to immunoblot analysis with anti-ARG and anti-Flag (right panel). Lysates not subjected to immunoprecipitation were analyzed by immunoblotting with the indicated antibodies (left and right panels). B, lysates from 293 cells expressing Flag-ARG were incubated with GST-Siva-1 or GST. Adsorbates were analyzed by immunoblotting with anti-Flag. Total lysate (TL) was used as a control. C and D, lysates from 293 cells expressing GFP-Siva-1 (C) or GFP-Siva-2 (D) were incubated with GST-ARG SH2, GST-ARG SH3, or GST. Adsorbates were subjected to immunoblotting with anti-GFP.

To determine whether Siva-1 is a substrate for ARG, GST-Siva-1 was incubated with kinase-active ARG (Fig. 2A, left) in the presence of [gamma -32P]ATP. Analysis of the reaction products by SDS-PAGE and autoradiography demonstrated phosphorylation of Siva-1 (Fig. 2A, right). As a control, there was no detectable phosphorylation when Siva-1 was incubated with kinase-inactive ARG(K-R) in which Lys337 in the ATP binding site was mutated to Arg (Fig. 2A). There are two potential tyrosine phosphorylation sites in Siva-1 that are located at Tyr48 and Tyr67. Mutation of these sites to Phe and then incubation of the mutant proteins with ARG demonstrated abrogation of phosphorylation with GST-Siva-1(Y48F), but not with GST-Siva-1(Y67F) (Fig. 2A, right). To assess whether ARG phosphorylates Siva-1 in vivo, Flag-Siva-1 was coexpressed with ARG and lysates were analyzed by immunoblotting with anti-P-Tyr. The results show that Siva-1 is phosphorylated by ARG in cells (Fig. 2B). By contrast, there was no detectable tyrosine phosphorylation of Flag-Siva-1 when this vector was coexpressed with ARG(K-R) (data not shown). Although Flag-Siva-1(Y67F) was also phosphorylated by ARG, there was no detectable tyrosine phosphorylation of Flag-Siva-1(Y48F) (Fig. 2B). In concert with these findings and the presence of Tyr48 in Siva-2, coexpression of Siva-2 with ARG, but not ARG(K-R), also resulted in detectable tyrosine phosphorylation (Fig. 2B). These findings thus provided support for ARG-mediated phosphorylation of Siva-1 and Siva-2 on Tyr48 in vitro and in vivo. To determine whether ARG, like c-Abl (20, 21), is activated by ROS, cells expressing Flag-ARG were treated with H2O2. Analysis of anti-Flag immunoprecipitates for phosphorylation of GST-Siva-1 demonstrated H2O2 concentration-dependent induction of ARG activity (Fig. 2C). As a control, the same anti-Flag immunoprecipitates failed to phosphorylate GST-Siva-1(Y48F) (Fig. 2C). In studies of wild-type and arg-/- MEFs, expression of Flag-Siva-1 resulted in little if any detectable phosphorylation (Fig. 2D). Treatment of the wild-type cells with H2O2, however, was associated with tyrosine phosphorylation of Flag-Siva-1 (Fig. 2D). By contrast, there was no detectable phosphorylation of Flag-Siva-1 in H2O2-treated arg-/- MEFs (Fig. 2D). These findings demonstrate that activation of ARG by H2O2 is associated with phosphorylation of Siva-1 on Tyr48.



View larger version (50K):
[in this window]
[in a new window]
 
Fig. 2.   ARG phosphorylation of Siva-1 in response to oxidative stress. A, Flag-ARG and Flag-ARG(K-R) (left panel) were incubated with GST-Siva-1, GST-Siva-1(Y67F), or GST-Siva-1(Y48F). GST-Crk-(120-225) was used as a positive control. Reaction products were analyzed by SDS-PAGE and autoradiography (right panel). B, 293 cells were cotransfected with ARG and Flag-Siva-1, Flag-Siva-1(Y48F), Flag-Siva-1(Y67F), or Flag-Siva-2. Lysates were subjected to immunoblotting (IB) with anti-P-Tyr and anti-Flag. C, 293 cells were transfected to express Flag-ARG. At 36 h after transfection, the cells were treated with the indicated concentrations of H2O2 for 2 h. Anti-Flag immunoprecipitates (IP) were subjected to ARG kinase assays using Siva-1 or Siva-1(Y48F) as substrate. D, wild-type (arg+/+) and arg-/- MEFs expressing Flag-Siva-1 were treated with 1 mM H2O2 for 2 h. Anti-Flag immunoprecipitates were analyzed by immunoblotting with anti-P-Tyr and anti-Flag.

To assess the functional significance of the ARG-Siva-1 interaction, MCF-7 cells were prepared that stably express ARG or the ARG(K-R) mutant. There was no detectable effect of ARG or ARG(K-R) expression on MCF-7 cell growth (data not shown) or cell cycle distribution (Fig. 3A). Expression of Siva-1 in the wild-type MCF-7 cells was associated with the appearance of apoptotic cells containing sub-G1 DNA (Fig. 3A). Whereas Siva-1-induced apoptosis was more pronounced in MCF-7/ARG cells, expression of Siva-1 had little if any effect on MCF-7/ARG(K-R) cells (Fig. 3A). As a control, expression of Siva-2 resulted in substantially less apoptosis in MCF-7/ARG cells as compared with that obtained with Siva-1, and had no effect on the wild-type MCF-7 and MCF-7/ARG(K-R) cells (Fig. 3A). To extend these findings, Siva-1 was expressed in the wild-type and arg-/- MEFs. The results demonstrate that, although Siva-1 induces apoptosis in wild-type cells, there was little effect of Siva-1 in the absence of ARG expression (Fig. 3B). In concert with the finding that ARG phosphorylates Siva-1 on Tyr48, the expression of Siva-1(Y48F) had little effect on the induction of apoptosis, whereas the proapoptotic effects of Siva-1(Y67F) were similar to those obtained with wild-type Siva-1 (Fig. 3C). These findings demonstrate that Siva-1-induced apoptosis is dependent on the ARG kinase function and that ARG-mediated phosphorylation of Siva-1 on Tyr48 is a proapoptotic signal.



View larger version (26K):
[in this window]
[in a new window]
 
Fig. 3.   Interaction of ARG and Siva-1 in the apoptotic response to oxidative stress. A, MCF-7, MCF-7/ARG, and MCF-7/ARG(K-R) cells were transfected to express GFP-Siva-1 or GFP-Siva-2. At 36 h after transfection, GFP-positive cells were analyzed for sub-G1 DNA (left panels). Cells with sub-G1 DNA are depicted in the shaded profiles. GO/G1 and G2/M cells are shown in the dark profiles and S phase cells in the hatched profiles. Cells were subjected to immunoblot analysis (IB) with the indicated antibodies (right panels). B, wild-type (arg+/+) and arg-/- MEFs were infected with empty or Siva-1 retroviral vectors for 24 h. The cells were analyzed by flow cytometry (left panels) and immunoblotting (right panels). C, MCF-7 (open bars), MCF-7/ARG (hatched bars), and MCF-7/ARG(K-R) (solid bars) were transfected with GFP-Siva-1, GFP-Siva-2, GFP-Siva-1(Y48F), or GFP-Siva-1(Y67F). GFP-positive cells were analyzed for DNA content. The results are expressed as the percentage (mean ± S.E. of two independent experiments each performed in duplicate) of GFP-positive cells with sub-G1 DNA.

As the findings demonstrate that ARG is activated by ROS, H2O2-induced apoptosis was assessed in the MCF-7, MCF-7/ARG, and MCF-7/ARG(K-R) cells. The results demonstrate that the apoptotic effects of H2O2 are attenuated in MCF-7/ARG(K-R) as compared with wild-type MCF-7 cells (Fig. 4A). Notably, however, there was a marked increase in H2O2-induced apoptosis in MCF-7/ARG cells (Fig. 4A). The apoptotic effects of H2O2 were attenuated in arg-/- (two separate embryos) as compared with wild-type MEFs (Fig. 4B). Moreover, expression of ARG in arg-/- cells corrected the defect in H2O2-induced apoptosis (Fig. 4C).



View larger version (21K):
[in this window]
[in a new window]
 
Fig. 4.   Apoptotic response to oxidative stress is ARG kinase-dependent. A---C, the indicated cells were left untreated (open bars) or treated with 1 mM H2O2 for 2 h (hatched bars), washed, and then cultured for 18 h. In C, arg+/- cells were prepared by transduction of arg-/- MEFs with a retroviral vector expressing ARG (transduction efficiency, >95% as determined by GFP expression). Cells were analyzed for DNA content. The results are expressed as the percentage (mean ± S.E. of two independent experiments performed in duplicate) of cells with sub-G1 DNA.

The ARG tyrosine kinase has, like c-Abl, been associated with the development of leukemia (25, 26). Despite the relatedness to c-Abl and a role in neurolation as defined in arg-/- mice (10), a function for ARG in cell signaling has remained obscure. Genetic studies in Drosophila have indicated that Abl family kinases regulate cellular morphology through interactions with the cytoskeleton (27, 28). The identification of actin-binding domains in the C-terminal region of ARG (3) and localization of ARG with actin microfilaments (10) have supported a role in regulation of the actin cytoskeletion. The present results provide evidence for involvement of ARG in the cellular response to oxidative stress. Moreover, the induction of apoptosis by oxidative stress is attenuated in ARG-deficient cells. These findings indicate that, in addition to regulating the actin cytoskeleton, ARG functions in ROS-mediated signals that induce an apoptotic response.

Siva-1 interacts with members of the tumor necrosis factor receptor family and induces apoptosis in diverse cells (22). Siva-1 has also been implicated in the induction of Coxsackievirus-induced apoptosis (29). Full-length Siva-1 but not Siva-2, which lacks sequences encoded by exon 2, induces the apoptotic response (23). The present studies demonstrate that ARG phosphorylates both Siva-1 and Siva-2. By contrast, the interaction between ARG and Siva-1, but not Siva-2, is associated with the induction of apoptosis. Our results also demonstrate that mutation of the Siva-1 Tyr48 site abrogates the apoptotic function of Siva-1 and that apoptosis induced by Siva-1 is dependent on expression of kinase-active ARG. These findings thus define ARG as an upstream effector of Siva-1 in the apoptotic response to oxidative stress.


    FOOTNOTES

* This investigation was supported by Grant CA42802 awarded by the NCI, National Institutes of Health.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.

|| To whom correspondence should be addressed: Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney St., Boston, MA 02115. Tel.: 617-632-3141; Fax: 617-632-2934; E-mail: donald_kufe@dfci.harvard.edu.

Published, JBC Papers in Press, February 23, 2001, DOI 10.1074/jbc.C100050200


    ABBREVIATIONS

The abbreviations used are: ARG, Abl-related gene; DNA-PK, DNA-dependent protein kinase; ROS, reactive oxygen species; PKC, protein kinase C; GST, glutathione S-transferase; GFP, green fluorescence protein; PAGE, polyacrylamide gel electrophoresis; MEF, mouse embryo fibroblast; SH2/SH3, Src homology 2 and 3 (domains).


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES


1. Goff, S. P., Gilboa, E., Witte, O. N., and Baltimore, D. (1980) Cell 22, 777-785[Medline] [Order article via Infotrieve]
2. Kruh, G. D., Perego, R., Miki, T., and Aaronson, S. A. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 5802-5806[Abstract]
3. Van Etten, R. A., Jackson, P. K., Baltimore, D., Sanders, M. C., Matsuddaira, P. T., and Janmey, P. A. (1994) J. Cell Biol. 124, 325-340[Abstract]
4. Wang, B., and Kruh, G. D. (1996) Oncogene 13, 193-197[Medline] [Order article via Infotrieve]
5. Van Etten, R. A., Jackson, P., and Baltimore, D. (1989) Cell 58, 669-678[Medline] [Order article via Infotrieve]
6. Kipreos, E. T., and Wang, J. Y. (1990) Science 248, 217-220[Medline] [Order article via Infotrieve]
7. Kipreos, E. T., and Wang, J. Y. (1992) Science 256, 382-385[Medline] [Order article via Infotrieve]
8. Tybulewicz, V. L. J., Crawford, C. E., Jackson, P. K., Bronson, R. T., and Mulligan, R. C. (1991) Cell 65, 1153-1163[Medline] [Order article via Infotrieve]
9. Schwartzberg, P. L., Stall, A. M., Hardin, J. D., Bowdish, K. S., Humaran, T., Boast, S., Harbison, M. L., Robertson, E. J., and Goff, S. P. (1991) Cell 65, 1165-1175[Medline] [Order article via Infotrieve]
10. Koleske, A. J., Gifford, A. M., Scott, M. L., Nee, M., Bronson, R. T., Miczek, K. A., and Baltimore, D. (1998) Neuron 21, 1259-1272[Medline] [Order article via Infotrieve]
11. Kharbanda, S., Ren, R., Pandey, P., Shafman, T. D., Feller, S. M., Weichselbaum, R. R., and Kufe, D. W. (1995) Nature 376, 785-788[CrossRef][Medline] [Order article via Infotrieve]
12. Kharbanda, S., Pandey, P., Jin, S., Inoue, S., Bharti, A., Yuan, Z.-M., Weichselbaum, R., Weaver, D., and Kufe, D. (1997) Nature 386, 732-735[CrossRef][Medline] [Order article via Infotrieve]
13. Jin, S., Kharbanda, S., Mayer, B., Kufe, D., and Weaver, D. T. (1997) J. Biol. Chem. 272, 24763-24766[Abstract/Free Full Text]
14. Shafman, T., Khanna, K. K., Kedar, P., Spring, K., Kozlov, S., Yen, T., Hobson, K., Gatei, M., Zhang, N., Watters, D., Egerton, M., Shiloh, Y., Kharbanda, S., Kufe, D., and Lavin, M. F. (1997) Nature 387, 520-523[CrossRef][Medline] [Order article via Infotrieve]
15. Baskaran, R., Wood, L. D., Whitaker, L. L., Xu, Y., Barlow, C., Canman, C. E., Morgan, S. E., Baltimore, D., Wynshaw-Boris, A., Kastan, M. B., and Wang, J. Y. J. (1997) Nature 387, 516-519[CrossRef][Medline] [Order article via Infotrieve]
16. Yuan, Z. M., Huang, Y., Whang, Y., Sawyers, C., Weichselbaum, R., Kharbanda, S., and Kufe, D. (1996) Nature 382, 272-274[CrossRef][Medline] [Order article via Infotrieve]
17. Yuan, Z. M., Shioya, H., Ishiko, T., Sun, X., Huang, Y., Lu, H., Kharbanda, S., Weichselbaum, R., and Kufe, D. (1999) Nature 399, 814-817[CrossRef][Medline] [Order article via Infotrieve]
18. Gong, J., Costanzo, A., Yang, H., Melino, G., Kaelin JR, W., Levrero, M., and Wang, J. Y. J. (1999) Nature 399, 806-809[CrossRef][Medline] [Order article via Infotrieve]
19. Agami, R., Blandino, G., Oren, M., and Shaul, Y. (1999) Nature 399, 809-813[CrossRef][Medline] [Order article via Infotrieve]
20. Sun, X., Wu, F., Datta, R., Kharbanda, S., and Kufe, D. (2000) J. Biol. Chem. 275, 7470-7473[Abstract/Free Full Text]
21. Sun, X., Majumder, P., Shioya, H., Wu, F., Kumar, S., Weichselbaum, R., Kharbanda, S., and Kufe, D. (2000) J. Biol. Chem. 275, 17237-17240[Abstract/Free Full Text]
22. Prasad, K. V., Ao, Z., Yoon, Y., Wu, M. X., Rizk, M., Jacquot, S., and Schlossman, S. F. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 6346-6351[Abstract/Free Full Text]
23. Yoon, Y., Ao, Z., Cheng, Y., Schlossman, S. F., and Prasad, K. V. (1999) Oncogene 18, 7174-7179[CrossRef][Medline] [Order article via Infotrieve]
24. Yuan, Z., Huang, Y., Ishiko, T., Kharbanda, S., Weichselbaum, R., and Kufe, D. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 1437-1440[Abstract/Free Full Text]
25. Cazzaniga, G., Tosi, S., Aloisi, A., Giudici, G., Daniotti, M., Pioltelli, P., Kearney, L., and Biondi, A. (1999) Blood 94, 4370-4373[Abstract/Free Full Text]
26. Iijima, Y., Ito, T., Oikawa, T., Eguchi, M., Eguchi-Ishimae, M., Kamada, N., Kishi, K., Asano, S., Sakaki, Y., and Sato, Y. (2000) Blood 95, 2126-2131[Abstract/Free Full Text]
27. Gertler, F. B., Bennett, R. L., Clark, M. J., and Hoffmann, F. M. (1989) Cell 58, 103-113[Medline] [Order article via Infotrieve]
28. Gertler, F. B., Hill, K. K., Clark, M. J., and Hoffman, F. M. (1993) Genes Dev. 7, 441-453[Abstract]
29. Henke, A., Launhardt, H., Klement, K., Stelzner, A., Zell, R., and Munder, T. (2000) J. Virol. 74, 4284-4290[Abstract/Free Full Text]


Copyright © 2001 by The American Society for Biochemistry and Molecular Biology, Inc.