Figure 4.
(A) Effects of carfilzomib (Cfz) on the viability of an RPMI8266 cell line with acquired Cfz resistance (RPMI8266/CfzR) in comparison to the parental cell line. Cell viability was measured by MTS assay after 72 h drug treatment (left). Immunoblotting analysis showing a marked increase of P-gp expression in RPMI8226 Cfz-resistant cells in comparison to parental cells (right). (B) Comparison of the sensitivity (72-h IC50 values) of RPMI8226 parental and Cfz-resistant cells to Cfz, epoxomicin, UK101, and UK102. Data are reported as the mean ± SD. For epoxomicin and carfilzomib, the SD values were obtained from three independent experiments. For UK101 and UK102, the SD values were from nonlinear regression analysis using three replicates.