Cbl: many adaptations to regulate protein tyrosine kinases

Nature Reviews Molecular Cell Biology - Tập 2 Số 4 - Trang 294-307 - 2001
Christine B.F. Thien1, Wallace Y. Langdon2
1Department of Pathology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
2Department of Pathology, University of Western Australia, Crawley, Australia.

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Langdon, W. Y., Hartley, J. W., Klinken, S. P., Ruscetti, S. K. & Morse, H. C.,III . v-cbl, an oncogene from a dual-recombinant murine retrovirus that induces early B-lineage lymphomas. Proc. Natl Acad. Sci. USA 86, 1168?1172 (1989).

Blake, T. J., Shapiro, M., Morse, H. C.,III & Langdon, W. Y. The sequences of the human and mouse c-cblproto-oncogenes show v-cbl was generated by a large truncation encompassing a proline-rich domain and a leucine zipper-like motif. Oncogene 6, 653?657 (1991).

Keane, M. M., Rivero-Lezcano, O. M., Mitchell, J. A., Robbins, K. C. & Lipkowitz, S. Cloning and characterization of cbl-b: a SH3-binding protein with homology to the c-cbl proto-oncogene. Oncogene 10, 2367?2377 ( 1995).

Keane, M. M. et al. cbl-3: a new mammalian cbl family protein. Oncogene 18, 3365?3375 ( 1999).

Meisner, H. et al. Interactions of Drosophilia Cbl with epidermal growth factor receptors and role of Cbl in R7 photoreceptor cell development. Mol. Cell. Biol. 17, 2217?2225 (1997).

Hime, G. R., Dhungat, M. P., Ng, A. & Bowtell, D. D. L. D-Cbl, the Drosophila homologue of the c-Cbl proto-oncogene, interacts with the Drosophila EGF receptor in vivo, despite lacking C-terminal adaptor binding sites. Oncogene 14, 2709? 2719 (1997).

Robertson, H., Hime, G. H., Lada, H. & Bowtell, D. D. L. A Drosophila analogue of v-Cbl is a dominant-negative oncoprotein in vivo. Oncogene 19, 3299?3308 ( 2000).

Yoon, C. H., Lee, J., Jongeward, G. D. & Sternberg, P. W. Similarity of sli-1, a regulator of vulval development in C. elegans , to the mammalian proto-oncogene c-cbl. Science 269, 1102?1105 (1995). A seminal publication that identified Cbl as a negative regulator of receptor tyrosine kinases.

Galisteo, M. L., Dikic, I., Batzer, A. G., Langdon, W. Y. & Schlessinger, J. Tyrosine phosphorylation of the c-cbl proto-oncogene product and association with epidermal growth factor (EGF) receptor upon EGF stimulation. J. Biol. Chem. 270, 20242? 20245 (1995).First demonstration that the amino-terminal half of c-Cbl can bind directly to tyrosine-phosphorylated epidermal growth factor receptor. This finding was further characterized in reference 10.

Lupher, M. L. Jr, Reedquist, K. A., Miyake, S., Langdon, W. Y. & Band, H. A novel PTB domain in the N-terminal transforming region of Cbl interacts directly and selectively with ZAP-70 in T cells. J. Biol. Chem. 271, 24063? 24068 (1996).

Bonita, D. P., Miyake, S., Lupher Jr, M. L., Langdon, W. Y. & Band, H. Phosphotyrosine binding domain-dependent upregulation of the platelet-derived growth factor receptor α signaling cascade by transforming mutants of Cbl: implications for Cbl's function and oncogenicity. Mol. Cell. Biol. 17, 4597? 4610 (1997).

Thien, C. B. F. & Langdon, W. Y. EGF receptor binding and transformation by v-cbl is ablated by the introduction of a loss-of-function mutation from the Caenorhabditis elegans sli-1 gene. Oncogene 14, 2239?2249 ( 1997).

Lupher, M. L. Jr et al. Cbl-mediated negative regulation of the Syk tyrosine kinase . J. Biol. Chem. 273, 35273? 35281 (1998).

Deckert, M., Elly, C., Altman, A. & Liu, Y. C. Coordinated regulation of the tyrosine phosphorylation of Cbl by Fyn and Syk tyrosine kinases. J. Biol. Chem. 273, 8867?8874 (1998).

Meng, W., Sawasdikosol, S., Burakoff, S. J. & Eck, M. J. Structure of the amino-terminal domain of Cbl complexed to its binding site on ZAP-70 kinase. Nature 398, 84? 90 (1999).The structure of Cbl's novel TKB domain revealed three interacting domains comprising a four-helix bundle, a Ca2+-binding EF hand and a variant SH2 domain.

Waterman, H., Levkowitz, G., Alroy, I. & Yarden, Y. The RING finger of c-Cbl mediates desensitization of the epidermal growth factor. J. Biol. Chem. 274, 22151?22154 (1999).

Joazeiro, C. A. P. et al. The tyrosine kinase negative regulator c-Cbl as a RING-type, E2-dependent ubiquitin-protein ligase. Science 286, 309?312 (1999).This paper, along with references 18 and 19 , was the first to define Cbl as an E3 ubiquitin protein ligase.

Levkowitz, G. et al. Ubiquitin ligase activity and tyrosine phosphorylation underlie suppression of growth factor signaling by c-Cbl/Sli-1. Mol. Cell 4, 1?20 (1999 ).

Yokouchi, M. et al. Ligand-induced ubiquitination of the epidermal growth factor receptor involves the interaction of the c-Cbl RING finger and UbcH7. J. Biol. Chem. 274, 31707?31712 (1999).

Zheng, N., Wang, P., Jeffrey, P. D. & Pavletich, N. P. Structure of a c-Cbl?UbcH7 complex: RING domain function in ubiquitin-protein ligases. Cell 102, 533? 539 (2000).The structure revealed that UBCH7 has several interactions with c-Cbl's RING finger domain and a highly conserved α-helix at the carboxyl terminus of the linker domain. This paper helped to explain the why deletions in the linker α-helix convert Cbl to an oncogenic protein.

Wong, E. S. M., Lim, J., Low, B. C., Chen, Q. & Guy, G. R. Evidence for direct interaction between Sprouty and Cbl . J. Biol. Chem. 276, 5866? 5875 (2001).

Hacohen, N., Kramer, S., Sutherland, D., Hiromi, Y. & Kasnow, M. A. sprouty encodes a novel antagonist of FGF signaling that patterns apical branching of the Drosophila airways. Cell 92, 253? 263 (1998).

Casci, T., Vinòs, J. & Freeman, M. Sprouty, an intracellular inhibitor of Ras signaling . Cell 96, 655?665 (1999).

Liu, Y.-C., Elly, C., Yoshida, H., Bonnefoy-Berard, N. & Altman, A. Activation-modulated association of 14-3-3 proteins with Cbl in T cells. J. Biol. Chem. 271, 14591?14595 (1996).

Liu, Y. C. et al. Serine phosphorylation of Cbl induced by phorbol ester enhances its association with 14-3-3 proteins in T cells via a novel serine-rich 14-3-3-binding motif. J. Biol. Chem. 272, 9979? 9985 (1997).

Liu, Y. et al. Protein kinase C activation inhibits tyrosine phosphorylation of Cbl and its recruitment of Src homology 2 domain-containing proteins. J. Immunol. 162, 7095?7101 (1999).

Fernàndez, B., Czech, M. P. & Meisner, H. Role of protein kinase C in signal attenuation following T cell receptor engagement. J. Biol. Chem. 274, 20244?20250 (1999).

Feshchenko, E. A., Langdon, W. Y. & Tsygankov, A. Y. Fyn, Yes and Syk phosphorylation sites in c-Cbl map to the same tyrosine residues that become phosphorylated in activated T cells . J. Biol. Chem. 273, 8323? 8331 (1998).

Tezuka, T. et al. Physical and functional association of the cbl protooncogene product with an Src-family protein tyrosine kinase, p53/56lyn, in the B cell antigen receptor-mediated signaling. J. Exp. Med. 183, 675?680 ( 1996).

de Jong, R., ten Hoeve, J., Heisterkamp, N. & Groffen, J. Crkl is complexed with tyrosine-phosphorylated cbl in Ph-positive leukemia . J. Biol. Chem. 270, 21468? 21471 (1995).

Buday, L., Khwaja, A., Sipeki, S., Farago, A. & Downward, J. Interactions of Cbl with two adaptor proteins, Grb2 and Crk, upon T cell activation. J. Biol. Chem. 271 , 6159?6163 (1996).

Sattler, M. et al. The proto-oncogene product p120CBL and the adaptor proteins CRKL and c-CRK link c-ABL, p190BCR/ABL and p210BCR/ABL to the phosphatidylinositol-3′ kinase pathway . Oncogene 12, 839?846 (1996).

Ribon, V., Hubbell, S., Herrera, R. & Saltiel, A. R. The product of the cbl oncogene forms stable complexes in vivo with endogenous crk in a tyrosine phosphorylation-dependent manner. Mol. Cell. Biol. 16, 45?52 ( 1996).

Andoniou, C. E., Thien, C. B. F. & Langdon, W. Y. The two major sites of cbl tyrosine phosphorylation in abl-transformed cells select the crkL SH2 domain. Oncogene 12, 1981?1989 (1996).

Jain, S. K., Langdon, W. Y. & Varticovski, L. Tyrosine phosphorylation of p120 cbl in BCR/abl transformed hematopoietic cells mediates enhanced association with phosphatidylinositol 3-kinase. Oncogene 14, 2217? 2228 (1997).

Marengére, L. E. M. et al. Proto-oncoprotein Vav interacts with c-Cbl in activated thymocytes and peripheral T cells. J. Immunol. 159, 70?76 (1997).

Elly, C. et al. Tyrosine phosphorylation and complex formation of Cbl-b upon T cell receptor stimulation. Oncogene 18, 1147?1156 (1999).

Songyang, Z. et al. SH2 domains recognize specific phosphopeptide sequences. Cell 72, 767?778 ( 1993).

Hartley, D. & Corvera, S. Formation of c-Cbl-phosphatidylinositol 3-kinase complexes on lymphocyte membranes by a p56lck-independent mechanism. J. Biol. Chem. 271, 21939? 21943 (1996).

Liu, Y.-C., Elly, C., Langdon, W. Y. & Altman, A. Ras-dependent, Ca2+-stimulated activation of nuclear factor of activated T cells by a constitutively active Cbl mutant in T cells. J. Biol. Chem. 272, 168?173 ( 1997).

Hunter, S., Burton, E. A., Wu, S. C. & Anderson, S. M. Fyn associates with Cbl and phosphorylates tyrosine 731 in Cbl, a binding site for phosphatidylinositol 3-kinase. J. Biol. Chem. 274, 2097? 2106 (1999).

Hofmann, K. & Bucher, P. UBA domain: a sequence motif present in multiple enzyme classes of ubiquitin pathway. Trends. Biochem. Sci. 21, 172?173 ( 1996).

Wang, Y., Yeung, Y. G., Langdon, W. Y. & Stanley, E. R. c-cbl is transiently tyrosine-phosphorylated, ubiquitinated, and membrane-targeted following CSF-1 stimulation of macrophages. J. Biol. Chem. 271, 17?20 (1996). First paper to indicate a connection between c-Cbl and protein multi-ubiquitylation.

Miyake, S., Lupher, M. L. Jr, Druker, B. & Band, H. The tyrosine kinase regulator Cbl enhances the ubiquitination and degradation of the platelet-derived growth factor receptor α. Proc. Natl Acad. Sci. USA 95, 7927?7932 (1998).

Levkowitz, G. et al. c-Cbl/Sli-1 regulates endocytic sorting and ubiquitination of the epidermal growth factor receptor. Genes Dev. 12, 3663?3674 (1998). References 44 and 45 were the first to show that c-Cbl can function as a negative regulator of receptor tyrosine kinase signalling by directing the multi-ubiquitylation of activated receptors.

Lee, P. S. W. et al. The Cbl protooncoprotein stimulates CSF-1 receptor multiubiquitination and endocytosis, and attenuates macrophage proliferation. EMBO J. 18, 3616?3628 ( 1999).

Lill, N. L. et al. The evolutionarily conserved N-terminal region of Cbl is sufficient to enhance down-regulation of the epidermal growth factor receptor. J. Biol. Chem. 275, 367?377 (2000).

Bartkiewicz, M., Houghton, A. & Baron, R. Leucine zipper-mediated homodimerization of the adaptor protein c-Cbl. J. Biol. Chem. 274, 30887 ?30895 (1999).

Jongeward, G. D., Clandinin, T. R. & Sternberg, P. W. sli-1, a negative regulator of let-23-mediated signaling in C. elegans. Genetics 139, 1553?1566 (1995).

Pai, L.-M., Barcelo, G. & Schüpbach, T. D-Cbl, a negative regulator of the Egfr pathway, is required for dorsoventral patterning in Drosophila oogenesis. Cell 103, 51?61 ( 2000).

Tanaka, S., Neff, L., Baron, R. & Levy, J. Tyrosine phosphorylation and translocation of the c-cbl protein after activation of tyrosine kinase signaling pathways. J. Biol. Chem. 270, 14347?14351 (1995).

Bowtell, D. D. L. & Langdon, W. Y. The protein product of the c-cbl oncogene rapidly complexes with the EGF receptor and is tyrosine phosphorylated following EGF stimulation. Oncogene 11, 1561?1567 ( 1995).

Ettenberg, S. A. et al. cbl-b inhibits epidermal growth factor receptor signaling . Oncogene 18, 1855?1866 (1999).

Lupher, M. L., Songyang, Z., Shoelson, S. E., Cantley, L. C. & Band, H. The Cbl phosphotyrosine-binding domain selects a D(N/D)XpY motif and binds to the TyrP292 negative regulatory phosphorylation site of ZAP-70. J. Biol. Chem. 272, 33140 ?33144 (1997).

Kong, G. et al. Distinct tyrosine phosphorylation sites in ZAP-70 mediate activation and negative regulation of antigen receptor function. Mol. Cell. Biol. 16, 5026?5035 ( 1996).

Zhao, Q. & Weiss, A. Enhancement of lymphocyte responsiveness by a gain-of-function mutation of ZAP-70. Mol. Cell. Biol. 16, 6765?6774 (1996).

Galcheva-Gargova, Z., Theroux, S. J. & Davis, R. J. The epidermal growth factor receptor is covalently linked to ubiquitin. Oncogene 11, 2649? 2655 (1995).

Levkowitz, G. et al. c-Cbl is a suppressor of the Neu oncogene. J. Biol. Chem. 275, 35532?35539 ( 2000).

Stang, E., Johannessen, L. E., Knardal, S. L. & Madshus, I. H. Polyubiquitination of the epidermal growth factor receptor occurs at the plasma membrane upon ligand-induced activation. J. Biol. Chem. 275, 13940?13947 (2000).

Thien, C. B. F., Walker, F. & Langdon, W. Y. Ring finger mutations that abolish c-Cbl-directed polyubiquitination and downregulation of the EGF receptor are insufficient for cell transformation. Mol. Cell 7, 355 ?365 (2001).

Fang, D. et al. Cbl-b, a RING-type E3 ubiquitin ligase, targets phosphatidylinositol 3-kinase for ubiquitination in T cells. J. Biol. Chem. 276, 4872?4878 (2001).

Ueno, H. et al. Antisense repression of proto-oncogene c-Cbl enhances activation of the JAK-STAT pathway but not the Ras pathway in epidermal growth factor receptor signaling. J. Biol. Chem. 272, 8739?8743 (1997).

Ojaniemi, M., Langdon, W. Y. & Vuori, K. Oncogenic forms of Cbl abrogate the anchorage requirement but not the growth factor requirement for proliferation. Oncogene 16, 3159?3167 ( 1998).

Miyake, S., Mullane-Robinson, K. P., Lill, N. L., Douillard, P. & Band, H. Cbl-mediated negative regulation of platelet-derived growth factor receptor-dependent cell proliferation. J. Biol. Chem. 274, 16619?16628 (1999).

Broome, M. A., Galisteo, M. L., Schlessinger, J. & Courtneidge, S. A. The proto-oncogene c-Cbl is a negative regulator of DNA synthesis initiated by both receptor and cytoplasmic tyrosine kinases. Oncogene 18, 2908?2912 (1999).

Ota, Y. & Samelson, L. E. The product of the proto-oncogene c-Cbl ? a negative regulator of the Syk tyrosine kinase. Science 276, 418?420 ( 1997).First paper to show a negative regulatory role for Cbl towards a protein tyrosine kinase in mammalian cells.

Rao, N. et al. The linker phosphorylation site Tyr292 mediates the negative regulatory effect of Cbl on ZAP-70 in T cells. J. Immunol. 164, 4616?4626 (2000).

Ota, S. et al. The RING finger domain of Cbl is essential for negative regulation of the Syk tyrosine kinase. J. Biol. Chem. 275, 414?422 (2000).

Yasuda, T. et al. Cbl suppresses B cell receptor-mediated phospholipase C (PLC)-γ2 activation by regulating B cell linker protein-PLCγ2 binding. J. Exp. Med. 191, 641?650 (2000).

Murphy, M. A. et al. Tissue hyperplasia and enhanced T cell signalling via ZAP-70 in c-Cbl deficient mice. Mol. Cell. Biol. 18, 4872?4882 (1998).

Naramura, M., Kole, H. K., Hu, R.-J. & Gu, H. Altered thymic positive selection and intracellular signals in Cbl-deficient mice. Proc. Natl Acad. Sci. USA 95, 15547?15552 (1998).References 70 and 71 provided evidence that c-Cbl functions as a negative regulator of ZAP-70 and that ZAP-70 in c-Cbl−/− thymocytes can be activated in the absence of CD4 co-receptor stimulation.

Thien, C. B. F., Bowtell, D. D. L. & Langdon, W. Y. Perturbed regulation of ZAP-70 and sustained tyrosine phosphorylation of LAT and SLP-76 in c-Cbl-deficient thymocytes. J. Immunol. 162, 7133?7139 (1999).

Tanaka, S. et al. c-Cbl is downstream of c-Src in a signalling pathway necessary for bone resorption. Nature 383, 528? 531 (1996).

Sanjay, A. et al. Cbl associates with Pyk2 and Src to regulate Src kinase activity, α vβ3 integrin-mediated signaling, cell adhesion, and osteoclast motility. J. Cell. Biol. 152, 181?195 (2001).

Meng, F. & Lowell, C. A. A β1 integrin signaling pathway involving Src-family kinases, Cbl and PI-3 kinase is required for macrophage spreading and migration. EMBO J. 17, 4391 ?4403 (1998).

Andoniou, C. E. et al. The Cbl proto-oncogene product negatively regulates the Src-family tyrosine kinase Fyn by enhancing its degradation. Mol. Cell. Biol. 20, 851?867 ( 2000).

Donovan, J. A., Wange, R. L., Langdon, W. Y. & Samelson, L. E. The protein product of the c-cbl protooncogene is the 120-kDa tyrosine-phosphorylated protein in Jurkat cells activated via the T cell antigen receptor. J. Biol. Chem. 269, 22921?22924 (1994).

Rellahan, B. L., Graham, L. J., Stocia, B., DeBell, K. E. & Bonvini, E. Cbl-mediated regulation of T cell receptor-induced AP-1 activation. J. Biol. Chem. 272 , 30806?30811 (1997).

Zhang, Z., Elly, C., Altman, A. & Liu, Y.-C. Dual regulation of T cell receptor-mediated signaling by oncogenic Cbl mutant 70Z. J. Biol. Chem. 274, 4883?4889 (1999).

Zhang, Z., Elly, C., Qiu, L., Altman, A. & Liu, Y.-C. A direct interaction between the adaptor protein Cbl-b and the kinase Zap-70 induces a positive signal in T cells. Curr. Biol. 9, 203?206 ( 1999).

van Leeuwen, J. E. M., Paik, P. K. & Samelson, L. E. Activation of nuclear factor of activated T cells (NFAT) and activating protein 1 (AP-1) by oncogenic 70Z Cbl requires an intact phosphotyrosine binding domain but not Crk(L) or p85 phosphatidylinositol 3-kinase association. J. Biol. Chem. 274, 5153?5162 (1999).

van Leeuwen, J. E. M., Paik, P. K. & Samelson, L. E. The oncogenic 70Z Cbl mutation blocks the phosphotyrosine binding domain-dependent negative regulation of ZAP-70 by c-Cbl in Jurkat T cells. Mol. Cell. Biol. 19, 6652? 6664 (1999).

Boussiotis, V. A., Freeman, G. J., Berezovskaya, A., Barber, D. L. & Nadler, L. M. Maintenance of human T cell anergy: blocking of IL-2 gene transcription by activated Rap1. Science 278, 124?128 ( 1997).

Chan, A. C. et al. Activation of ZAP-70 kinase activity by phosphorylation of tyrosine 493 is required for lymphocyte antigen receptor function. EMBO J. 14, 2499?2508 ( 1995).

Wange, R. L. et al. Activating and inhibitory mutations in adjacent tyrosines in the kinase domain of ZAP-70. J. Biol. Chem. 270, 18730?18733 (1995).

Bachmaier, K. et al. Negative regulation of lymphocyte activation and autoimmunity by the molecular adaptor Cbl-b. Nature 403, 211?216 (2000).

Chiang, Y. J. et al. Cbl-b regulates the CD28 dependence of T-cell activation. Nature 403, 216?220 ( 2000).

Krawczyk, C. et al. Cbl-b is a negative regulator of receptor clustering and raft aggregation in T cells. Immunity 13, 463 ?473 (2000).References 86 88 provided evidence that Cbl-b selectively suppresses TCR-mediated Vav activation and that Cbl-b-deficient mice are highly susceptible to autoimmune disease.

Bustelo, X. R., Crespo, P., López-Barahona, M., Gutkind, J. S. & Barbacid, M. Cbl-b, a member of the Sli-1/c-Cbl protein family, inhibits Vav-mediated c-Jun N-terminal kinase activation. Oncogene 15, 2511?2520 ( 1997).

Andoniou, C. E., Thien, C. B. F. & Langdon, W. Y. Tumour induction by activated abl involves tyrosine phosphorylation of the product of the cbl oncogene. EMBO J. 13, 4515?4523 ( 1994).Identified an acutely transforming c-Cbl protein in the 70Z/3 mouse pre-B cell lymphoma. This form of c-Cbl has 17-amino-acid deletion spanning the α-helix of the linker domain (that separates the SH2 and RING finger domains) and the first two residues of the RING finger.

Thien, C. B. F. & Langdon, W. Y. Tyrosine kinase activity of the EGF receptor is enhanced by the expression of oncogenic 70Z-Cbl . Oncogene 15, 2909?2919 (1997).

Feshchenko, E. A., Shore, S. K. & Tsygankov, A. Y. Tyrosine phosphorylation of c-Cbl facilitates adhesion and spreading while suppressing anchorage-independent growth of v-Abl-transformed NIH3T3 fibroblasts. Oncogene 18, 3703? 3715 (1999).

Scaife, R. M. & Langdon, W. Y. c-Cbl localizes to actin lamellae and regulates lamellipodia formation and cell morphology. J. Cell Sci. 113, 215?226 ( 2000).

Graham, L. J. et al. Differential effects of Cbl and 70Z/3 Cbl on T cell receptor-induced phospholipase Cγ-1 activity. FEBS Lett. 470, 273?280 (2000).

Ueno, H. et al. c-Cbl is tyrosine-phosphorylated by interleukin-4 and enhances mitogenic and survival signals of interleukin-4 receptor by linking with the phosphatidylinositol 3'-kinase pathway. Blood 91, 46?53 (1998).

Grishin, A. et al. Involvement of Shc and Cbl-PI 3-kinase in Lyn-dependent proliferative signaling pathways for G-CSF. Oncogene 19, 97?105 (2000).

Garcia-Guzman, M., Larsen, E. & Vuori, K. The proto-oncogene c-Cbl is a positive regulator of Met-induced MAP kinase activation: a role for the adaptor protein Crk. Oncogene 19, 4058?4065 ( 2000).

Mastick, C. C. & Saltiel, A. R. Insulin-stimulated tyrosine phosphorylation of caveolin is specific for the differentiated adipocyte phenotype in 3T3-L1 cells. J. Biol. Chem. 272, 20706?20714 (1997).

Baumann, C. A. et al. CAP defines a second signalling pathway required for insulin-stimulated glucose transport. Nature 407, 202? 207 (2000).Identifies c-Cbl as a key adaptor molecule in a complex with CAP and flotillin. The complex is localized to lipid raft subdomains and mediates a second signal required for glucose transport.

Ojaniemi, M., Martin, S. S., Dolfi, F., Olefsky, J. M. & Vuori, K. The proto-oncogene product p120cbl links c-Src and phosphatidylinositol 3′-kinase to the integrin signaling pathway. J. Biol. Chem. 272, 3780? 3787 (1997).

Sattler, M. et al. Differential signaling after β1 integrin ligation is mediated through binding of CrkL to p120CBL and p110HEF1. J. Biol. Chem. 272, 14320 ?14326 (1997).

Zell, T. et al. Regulation of β1-integrin-mediated cell adhesion by the Cbl adaptor protein. Curr. Biol. 8, 814? 822 (1998).

Kirsch, K. et al. The adaptor type protein CMS/CD2AP binds to the proto-oncogenic protein c-Cbl through a tyrosine phosphorylation-regulated Src homology 3 domain interaction. J. Biol. Chem. 276, 4957?4963 (2001).

Uemura, N. & Griffin, J. D. The adapter protein Crkl links Cbl to C3G after integrin ligation and enhances cell migration. J. Biol. Chem. 274, 37525?37532 (1999).

Ribon, V., Herrera, R., Kay, B. K. & Saltiel, A. R. A role for CAP, a novel, multifunctional Src homology 3 domain-containing protein in formation of actin stress fibers and focal adhesion. J. Biol. Chem. 273, 4073?4080 ( 1998).

Take, H. et al. Cloning and characterization of a novel adaptor protein, CIN 85, that interacts with c-Cbl. Biochem. Biophys. Res. Comm. 268, 321?328 (2000).

Yoon, C. H., Chang, C., Hopper, N. A., Lesa, G. M. & Sternberg, P. W. Requirements of multiple domains of SLI-1, a Caenorhabditis elegans homologue of c-Cbl, and an inhibitory tyrosine in LET?23 in regulating vulval differentiation. Mol. Biol. Cell 11, 4019?4031 ( 2000).

Terrell, J., Shih, S., Dunn, R. & Hicke, L. A function for monoubiquitination in the internalization of a G protein-coupled receptor. Mol. Cell 1, 193?202 ( 1998).

Nakatsu, F. et al. A di-leucine signal in the ubiquitin moiety. J. Biol. Chem. 275, 26213?26219 (2000).

Thrower, J. S., Hoffman, L., Rechsteiner, M. & Pickart, C. M. Recognition of the polyubiquitin proteolytic signal. EMBO J. 19, 94?102 (2000).

Bonifacino, J. S. & Weissman, A. M. Ubiquitin and the control of protein fate in the secretory and endocytic pathways. Annu. Rev. Cell Dev. Biol. 14, 19? 57 (1998).

Ciechanover, A. The ubiquitin-proteasome pathway: on protein death and cell life. EMBO J. 17, 7151?7160 ( 1998).