Identification of a Bcr-Abl kinase signature. (A) A pathway diagram of the 16 common proteins from Table 2 with cellular localization is shown. The proteins without highlighting were found in the Bcr-Abl–containing cells and U937 cells and were therefore not considered part of a signature for Bcr-Abl. The 6 signature proteins with a previous link to Bcr-Abl were highlighted in green (Abl, Bcr, Cbl, SHIP-2, Shc, and VASP). The signature proteins not previously identified in Bcr-Abl signaling are highlighted in blue (CD2AP and GRF1). (B) Expression of 2 novel human signature proteins in Bcr-Abl–containing (BV173 and K562) and control (EoL-1) cells was confirmed by Western blotting using antibodies to total CD2AP and VASP. (C) Phosphorylation in Bcr-Abl–containing cells was validated using antiphosphotyrosine immunoprecipitation followed by Western blotting using total CD2AP or VASP antibodies. Immunoblotting for p-cdc2 (Y15) was used to control for the efficiency of the phosphotyrosine immunoprecipitation because this site is ubiquitously phosphorylated in cell lines.