FIG. 1.

Vav2 is tyrosine phosphorylated in response to growth factors but not in response to adhesion to ECM. (a) Upper panel: antiphosphotyrosine blot of endogenous Vav2 immunoprecipitated from HEK293 cells held in suspension (S) or plated on fibronectin (Fn) for 10, 20, 30, or 60 min. Bottom panel: the blot was stripped and reprobed for Vav2 with an anti-Vav2 antibody to compare the amounts of Vav2 immunoprecipitated for each time point. (b) Upper panel: antiphosphotyrosine blot of Vav2 immunoprecipitated from serum-starved HEK293 cells that were treated with EGF (100 ng/ml) for 0, 5, 10, 20, 30, 40, or 60 min. Bottom panel: the amount of Vav2 protein immunoprecipitated was compared by stripping the blot and reprobing with anti-Vav2 antibody. (c) Vav2 is tyrosine phosphorylated in response to PDGF-BB. NIH 3T3 cells were treated for 0, 10, and 20 min with PDGF-BB (50 ng/ml). Vav2 was immunoprecipitated and blotted for phosphotyrosine (upper panel), and Vav2 (lower panel).