Combination treatment with DOX and gamitrinib. (A) Gamitrinib sensitizes cancer cells to DOX treatment. HeLa, SK-OV3, and 22Rv1 cells were treated with various concentrations of DOX in the absence (open circles) or presence of 5 μM, 10 μM, and 2.5 μM gamitrinib (closed circles), respectively, for 24 hours. Cell viability was analyzed by MTT assay. Percent viability was expressed as a percentage relative to 0 μM DOX-treatment. (B) Effect of combination treatment on cardiomyocytes. Mouse primary cardiomyocytes were treated in the absence (open circles) or presence (closed circles) of 5 μM gamitrinib for 24 hours and analyzed by MTT assay. (C) Graphical representation of combination index (CI) for HeLa cells. The MTT data were analyzed using CalcuSyn software to generate CI values. The 95% confidence interval of CI (mean ± 1.96 × standard deviation) is depicted as dotted lines.