CRBN knockdown induces myeloma cell cytotoxicity. (A) Five lentiviral CRBN shRNA constructs were cotransfected with Flag-tagged CRBN cDNA expression constructs into 293 cells, and Western blot was performed at day 3 after transfection to measure flag-tagged CRBN level. Lentiviruses were prepared from 3 lentiviral CRBN shRNA constructs (1, 10, and 13) and the corresponding NT constructs and subsequently were used to infect 4 different myeloma cell lines. CRBN knockdown was detected by quantitative PCR at day 3 after infection (B), and the cell viability was measured by MTT assay at day 6 after infection (C). Cell cycle (D) and apoptosis assays (E) were performed on OPM2 cells at day 3 and day 5 after lentiviral infection, respectively.