PIs induced accumulation of MAF protein in MM cells. 8226 and ARK (A) cells were treated with 20 nM Bzb in the presence of 5 μg/mL CHX for indicated times. APR1 (B,E), MM144 (C-D) were treated with serial concentrations of Bzb (B-C), CFZ (D), or with 20 nM CFZ or 10 μM MG132 (E) for 6 hours in the presence of CHX. Cell lysates were isolated and MAF protein analyzed. Anti-β-actin or anti-tubulin was used to indicate protein loading for each cell line. MM144 cells were treated with serial concentrations of Bzb for 12 hours; MAF nuclei and cytoplasm expression was determined by immunofluorescence staining (F). 8226 cells were treated with indicated concentrations (0 or 20 nM) of Bzb or CFZ for 12 hours. MAF nuclei and cytoplasm expression was determined by immunofluorescence staining with DAPI counterstaining (G). Images were taken with a fluorescent microscope and digital camera.