Cells were plated, serum-starved overnight, pre-treated with indicated concentrations of Gp2 overnight for (A) MCF-7L, (B) MCF-7L TamR and 4 hours Gp2 pretreatment for (C) T47D, (D) T47D TamR before treating with either 10 nM IGF-I, 10 nM IGF-II or 10 nM insulin for 15 minutes. Whole cell lysates were separated by SDS-PAGE and immunoblotted with indicated antibodies.