Changes in Dox-induced cytotoxicity after p53 and Bak knockdown in EWS cells. The VH-64 or WE-68 parental cell lines were transfected with 20 nM of siRNA against p53 (A) or Bak (B). After 48 h incubation, the cells were collected, and qRT-PCR and an immunoblot analysis were performed to confirm the effects of the siRNA. The cells were seeded at 2 × 103 cells/well in 96 well plates and treated with various concentrations of doxorubicin for 48 h. The cell viability was determined by the CellTiter-GloTM Luminescent Cell Viability Assay. The data represent the means of three separate experiments. The results are the means ± SD. *, P < 0.05.