Figure 1.

P66shc stimulates rac1 activity and rac1-specific GEF activity of sos1. (A) Comparison of rac1 activity in MEF cell lines derived from p66shcWT (p66shc +/+) and p66shc −/− mice with rac1 activity in p66shc −/− MEF transiently transfected with empty vector or the indicated p66shc constructs. Expression of the Xpress-tagged p66shc constructs sos1, eps8, and e3b1 are shown at bottom. The black line indicates that intervening lanes have been spliced. (B, left) Comparison of rac1-specific GEF activity of immunoprecipitated sos1 in wild-type and p66shc −/− MEF (top) with p66shc −/− MEF transfected with empty vector or the indicated p66shc constructs (bottom). All cells were cotransfected with sos1, eps8, and e3b1. (right) Immunoprecipitated sos1. Error bars depict mean ± SEM.