Figure 3.

Differential requirement for RasGRP and Sos family in BCR- or EGFR-mediated Ras activation. (A) BCR-mediated Ras and ERK activation in wild-type, Sos1/Sos2 double-, RasGRP3-, and RasGRP1/RasGRP3 double-deficient DT40 cells. Ras and ERK activation was measured as described in Fig. 1. (B) EGFR-mediated Ras and ERK activation in each deficient DT40 cell. Cells were stimulated by 50 ng/ml EGF and analyzed as in Fig. 1. These experiments were performed at least three times and the representative results are shown.