Figure 4. Modulation of signaling following acute Src inactivation in Balb-A1 ts-Src cells and Ψ2 v-Src 3T3 cells.

A: The ts-Src oncoprotein was inactivated in serum-starved Balb-A1 ts-Src cells by shifting cells to 39.5°C. At various times post-inactivation of Src, cells were harvested and their proteins were analyzed by SDS-PAGE followed by Western blotting using antibodies directed against phospho-tyrosine (P-Tyr proteins); cleaved PARP (cl-PARP); phospho-STAT-3 (P-STAT3); STAT-3; phospho-Akt (P-Akt); Akt; phospho-ERK1/2 (P-ERK1/2); ERK1/2; phospho-p38 (P-p38); p38. Times post-inactivation of Src (in minutes and hours) are indicated at the top of each lane, the relative migration of the relevant proteins are indicated on the left-hand side of each autoradiogram and to the right of each autoradiogram are indicated the relative migration of molecular weight standards.

B: V-src oncoprotein was inactivated in serum-starved Ψ2 v-Src 3T3 cells by the addition of 3μM of SU-6656, a src-specific inhibitor. At various times post-inactivation of Src, cells were harvested and their proteins were analyzed by SDS-PAGE followed by Western blotting using antibodies directed against phospho-tyrosine (P-Tyr proteins); activated phospho-src (P-Src); total src; cleaved PARP (cl-PARP); full-length PARP (fl-PARP); phospho-STAT-3 (P-STAT3); STAT-3; phospho-Akt (P-Akt); Akt; phospho-ERK1/2 (P-ERK1/2); ERK1/2; phospho-p38 (P-p38); p38. Times post-inactivation of Src (in minutes and hours) are indicated at the top of each lane, the relative migration of the relevant proteins are indicated on the left-hand side of each autoradiogram and to the right of each autoradiogram are indicated the relative migration of molecular weight standards. In the top panel, arrows point to several unidentified proteins whose tyrosine phosphorylation appears to decrease upon v-src inactivation.