Effects of silencing of survivin expression on bortezomib sensitivity in HCT116p53-/- cells. The highly survivin expressing HCT116p53-/- cells at 50% confluence were transfected with survivin mRNA-specific siRNAs or with control siRNAs. After 16 hours post transfection, cells were treated with and without bortezomib for 48 hours. A part of the transfected cells were then collected for western blots to determine survivin expression (A), a part of the transfected cells was used to determine cell growth inhibition by MTT assay (B), and the other part of the transfected cells was used to determine cell death/DNA fragmentation by cell death ELISA assay (C). Data shown in B and C are the mean ± SD derived from three independent determinations. Note: Results from cells without transfection were similar to cells transfected with control siRNA/shRNA (not shown). The expression of survivin in HCT116p53-/- cells was set at 10 and relative survivin expression levels are shown after normalized to actin.