RGS10 alters cytotoxicity of cisplatin in multi-drug resistant HeyA8 cells. (A) RT-PCR indicates selective knock-down of RGS10 48 hours following transfection of MDR-HeyA8 cells with RGS10 siRNA. (B) siRNA mediated knock-down of RGS10 results in increased cell growth as determined by viability assays. *: p < 0.05 (C) Cisplatin was added at the indicated doses 24 hours after siRNA transfection, and cell viability was determined 48 hours after drug treatment. Data are shown normalized to cell viability in the absence of drug (100%). Inset: Relative cell viability of RGS10 siRNA transfected MDR-HeyA8 cells is significantly higher than control transfected cells in the presence of 40 μM cisplatin. **: p < 0.01. (D) Phosphatidylserine externalization was determined by annexin staining in MDR-HeyA8 cells transfected with control or RGS10 siRNA following 48 hour incubation with vehicle or 10 μM cisplatin. Annexin staining was determined using flow cytometry as described in Methods. 50,000 cells were analyzed for each data point.