Fig. 2. Response to tamoxifen in ER-a and EGFR-positive breast cancer cells. (A, B) EGFR and ER-a mRNA and protein were detected by real-time PCR (A) and western blots (B). (C) Cells were treated with 4-OHT at the indicated concentration for 24 h. Cell viability was analyzed by MTT assays. Results are representative of three independent experiments. Values are mean ± SEM. * P<0.05 vs. (-) control.