RGS6, not RGS7, drives chemotherapy-dependent death of breast cancer cells. (A and B) Female mice (n = 10) were treated with the carcinogen DMBA (1 mg/20 g body weight), and protein expression detected in breast tissue via (A) immunohistochemistry (n = 10) and (B) immunoblot (n = 4 to 5). (C) Colony formation in MCF7 or MDA-MB-231 cells following transfection of control (GFP), RGS6-GFP or RGS7-GFP (n = 8). (D) RGS7-GFP was transfected into MCF7 or MDA-MB-231 breast cancer cells and CM-H2-DCFDA fluorescence (total ROS; n = 6) and apoptosis (n = 6) measured. (E) MDA-MB-231 cells were treated with doxorubicin (2 µM, 12 h) following introduction of scramble or RGS7-shRNA and total ROS (n = 6); and apoptosis (n = 6) measured. MDA-MB-231 cells were treated with doxorubicin (2 µM, 12 h) following introduction of scramble or (F) RGS6- or (G) RGS7-shRNA. RGS6/7, p-p53, and p-ATM expression were determined.