Fig. 5.

Evidence of the involvement of ERα, Shc, and IGF-1R in E2-induced MAPK phosphorylation. (A) Down-regulation of ERα, Shc, and IGF-1R blocked E2-induced MAPK phosphorylation. Cells were transfected with specific and nonspecific siRNAs. At day 2, cells were treated with vehicle or E2 at 0.1 nM for 15 min, and then whole-cell extracts were prepared and analyzed by Western blotting as described in Materials and Methods. Polyvinylidene difluoride membranes were probed with antidual phosphotyrosine MAPK antibody. ^*, P < 0.05 comparison of E2-treated cells with the vehicle-treated control in each siRNA transfected group. (B) Selective pathway inhibitors on E2-induced MAPK phosphorylation. Cells were challenged with vehicle or 0.1 nM E2 for 15 min in the presence of the inhibitors, as indicated.