Ouabain enhances cytotoxicity of MMC against U2OS cells.

<p>(A) U2OS cells were pretreated with the 50 nM ouabain for 1 h and then treated with 2000 ng/ml MMC. After incubation for 48 h, cell viability was measured with the MTT assay. Values represent the means ± SEM from three independent experiments (Student’s <i>t</i>-test, ***, <i>P</i> < 0.001). (B) Protein extracts from U2OS cells treated as described in (A) were analyzed by Western blotting using antibodies against PARP-1. Proform of PARP (116 kDa) and cleaved PARP (85 kDa) are indicated.