Fig. 6

Loss of ERα and/or inhibition of ERα with tamoxifen and fulvestrant downregulate BRK expression in ER-positive breast cancer cells. a, b Lysate from MCF7 cells stably transfected with control shRNAs or shRNAs against ERα (a) or BRK (b) were analyzed by immunoblotting using antibodies against BRK and ERα, and β-tubulin as a loading control. c Immunoblot analysis of MCF7 cells treated with vehicle (DMSO) or increasing concentrations of fulvestrant (1–20 μM) for 24 h. d Quantification of immunoblots from (c). e Immunoblot analysis of MCF7, BT474, T47D and SKBR3 cells treated with vehicle (DMSO) or 4-hydroxytamoxifen (30 μM) for 24 h. f Quantification of immunoblots from (e). Protein expression was quantified using Image J software