Effect of bortezomib and ixazomib on human multiple myeloma cell viability. Viability of (A) bortezomib- and (B) ixazomib-treated KMS-20, KMS-26, and KMS-28BM cells, as measured by the trypan blue dye assay. These cells were treated with the indicated concentrations of bortezomib for 3 days. The results are representative of five independent experiments. * p < 0.01 vs. controls (viability of KMS-20 cells was analyzed by the Shapiro-Wilk test and one-way analysis of variance (ANOVA) with Dunnett’s test. The viability of the KMS-26 and KMS-28BM cells was analyzed by the Shapiro-Wilk and Kruskal-Wallis tests, followed by the Steel test). (C) half-maximal inhibitory concentration (IC50) of bortezomib and ixazomib for KMS-20, KMS-26, and KMS-28BM cells.