CLA induces apoptosis in ERα positive human breast cancer cell line. (A) ERα protein expression was examined by western blot of whole cell lysate isolated from MCF-7, MDA-MB-231 (parental), and MDA-MB-231-ERα (ERα transfected MDA-MB-231). Equal amounts of isolated protein from cell extracts of all three cell lines were subjected to immunoblot with anti-ERα antibodies. β-actin was used as loading control. Effects of CLA on apoptosis of MCF-7, MDA-MB-231, and MDA-MB-231-ERα were determined by Hoechst staining (B) and Apo-ONE® homogeneous caspase-3/7 assay (C). Bars represent mean ± SD, n = 3. *p < 0.05 stands for control versus 40 μM t10, c12-CLA.