Bim enhances bortezomib-induced apoptosis in the absence of Noxa in pG1 and in cooperation with Noxa in pG1-S. (A) Quantitative RT-PCR analysis of PMAIP1 and BCL2L11 mRNAs in MM1.S cells cultured as in Figure 1B. (B-C) Quantitative RT-PCR analysis of Bcl-2 family genes and immunoblotting of Bcl-2 family proteins and cleaved caspase-3 at 7 hours from BTZ pulsing (60nM) in control, pG1 or pG1-S (12 hours after PD withdrawal) cells. (D) Noxa mRNA and protein expression in MM1.S cells at 72 hours after infection with PMAIP1 or GFP shRNA lentivirus. (E) PMAIP1 or GFP shRNA (sh) lentivirus-infected MM1.S cells were treated with PD and BTZ (60nM) as indicated. MT⁻ and live cells were determined at 7 hours from BTZ pulsing. (F-G) BCL2L11 or GFP shRNA (sh) lentivirus-infected MM1.S cells were treated with PD and BTZ (60nM) as indicated. Bim protein levels and the percentages of MT⁻ cells were determined as indicated. (H) Immunoblotting of Bim in MM1.S and LP-1 myeloma cells (left). LP-1 cells were pulsed with BTZ (120nM) in pG1 (0.5μM PD, 24 hours) or pG1-S (4 hours after PD withdrawal). The percentage of live cells relative to non-BTZ–treated cells was determined 18 hours from BTZ pulsing (right). Data are representative of 3 independent experiments.