Effect of overexpression of PTP1B or TCPTP on the association of Grb2 with p210 bcr-abl. Cell lysates (300 μg) from p210 bcr-abl-transformed clone 5 overexpressing PTP1B, PTP1B-D181A, TCPTP, or a control vector were prepared, and p210 bcr-abl was immunoprecipitated by using anti-Abl antibody K12 (lanes A). Immunoprecipitates were resolved by SDS/PAGE, transferred to nitrocellulose, and immunoblotted with anti-Grb2 antibody (Upper) or anti-Abl antibody 8E9 (Lower), as a control to illustrate constant levels of p210 bcr-abl. Lanes L depict 25 μg of cell lysate. Immunoblots were visualized by ECL.