CASC3 and plasma cell myeloma: Following 24 h treatment with 15 nM BTZ, analysis of cell viability revealed that U266/FAC cells showed reduced percentage of apoptotic cells as compared to PCs not pretreated with FAC (U266) (U266/FAC + BTZ: 19.05 ± 0.5% versus U266 + BTZ: 28.75 ± 0.6%; % of apoptotic cells; Fig. 3A and B), thus supporting the hypothesis that iron mediates resistance to BTZ-induced cytotoxicity in myeloma cells.