Figure 7.

Effects of EGF, ECM, and V¹²Ras on ERK2 tyrosine phosphorylation. A: EGF stimulates ERK2 tyrosine phosphorylation in parental GECs adherent to collagen. GECs were plated onto collagen (C) or plastic (P) and were cultured in serum-poor medium for 18 hours. GECs were then incubated with (+) or without (−) EGF (100 ng/ml) for 1 hour at 37°C. Cell lysates were immunoprecipitated (IP) with anti-ERK antibody, and the immunoprecipitates were subjected to SDS-PAGE and immunoblotting with anti-phosphotyrosine (PY) antibody. B and C: ERK2 is tyrosine phosphorylated in V¹²Ras-transfected GECs (clone R514). GECs were cultured in serum-poor medium for 18 hours. Parental GECs on collagen were incubated with or without EGF (as in A). V¹²Ras-transfected GECs were incubated without EGF. Cell lysates (in duplicate) were immunoprecipitated and immunoblotted as indicated.