GO-203 promotes BTZ-induced MM cell death. (A-E) U266 and RPMI8226 cells were left untreated (CTL) and treated with (1) 2.5 μM GO-203 alone each day for 72 hours, (2) 9 nM BTZ for 24 hours, or (3) GO-203 for 48 hours combined with BTZ during an additional 24 hours. Where indicated, GO-203/BTZ-treated cells were also incubated in the presence of 5 mM NAC for 72 hours. Lysates were immunoblotted with the indicated antibodies (A-B). U266 cells were incubated with PI and annexin V and analyzed by flow cytometry (C, left). The percentage of PI+ and/or annexin V+ cells is included in the panels (C, left). The results are expressed as the percentage (mean ± SD of 3 determinations) of dead cells (C, right). Percentage survival (mean ± SD of 3 determinations) was determined by Alamar blue staining (D). The indicated cells were incubated with PI and annexin V and analyzed by flow cytometry (E-F).