Figure 7
PDZK1 interacts with the Src/ER-α/EGFR complex and enhances EGF-mediated signal transduction. (A) MCF-7 cells were treated with 1 nmol/L E2 for 48 h or left untreated, after which protein extracts were subjected to immunoprecipitation with antibodies against c-Src. The immunoprecipitates, along with 10% input, were subjected to immunoblot analysis with antibodies against c-Src, ER-α, PDZK1, EGFR or GAPDH. The same protein extracts were subjected to immunoprecipitation with control IgG followed by immunoblot analysis with antibodies against c-Src, PDZK1 or GAPDH (Supplementary Figure S8). (B) The same protein extracts were subjected to immunoprecipitation with antibodies against IGF-1R followed by immunoblot analysis with antibodies against PDZK1, IGF-1R or GAPDH. (C) MCF-7 cells were transiently transfected with siRNA targeting PDZK1 and were treated with 1 nmol/L E2 or left untreated for 48 h. In the absence of E2 cells were treated with 20 ng/mL EGF for different time intervals. Cells were collected and protein extracts were prepared and subjected to immunoblot analysis with antibodies against phospho-ERK1/2 (pERK), ERK, PDZK1 or GAPDH. Immunoblots for pERK were quantified by using Adobe Photoshop CS, and data are expressed as the fold-change from control. *Difference from untreated WT control; #difference from similarly E2-treated nontransfected cells; p < 0.05.