Sensitivity of RMS cells to Bortezomib and/or 17-DMAG exposure. (A) To assess cytotoxicity induced by Bortezomib and 17-DMAG, ARMS (RH30) and ERMS (RD) cells were exposed to increasing drug concentrations, and viability was measured by MTT assay after 24, 48, and 72 hours. Values, expressed as folds of control (untreated cells), represent means of three independent experiments. (B) Time- and dose-dependent effects of Bortezomib and 17-DMAG treatments were assessed in cells exposed to the thereof combination for up to 72 hours, using multiple drug concentrations (Bort. 5–7.5-20-50nM; 17-DMAG 10-20-50-100 nM) as indicated (B, Bortezomib; D, 17-DMAG). Cell viability was assessed by MTT assay, and data were expressed as described above. Values are means of three independent experiments. (C) Dose–response analysis of RH30 and RD cells treated for 48 hours with 7.5nM Bortezomib, 50nM 17-DMAG or the thereof combination is shown. Drug effectiveness of the Bortezomib/17-DMAG combination results significantly higher in comparison to that observed after both single-agent treatments (t-test analysis *, p < 0,05). Values are expressed as folds of control (untreated cells) and are means ± standard deviation of three independent experiments. ns: non significant.