Figure 4: Effects of XIAP silencing or reduced XIAP by silencing HuR on apoptotic sensitivity in polyamine-deficient cells. (A) Representative immunoblots for XIAP protein. Cells were grown in the cultures containing DFMO for 2 days and then transfected with either siRNA specifically targeting XIAP mRNA CR (siXIAP), siHuR or C-siRNA. The levels of XIAP protein were measured by western blot analysis 48 h after transfection. (B) TNF-α/CHXinduced apoptosis in cells described (A): (a) control cells; (b) DFMO-treated cells transfected with C-siRNA; (c) DFMO-treated cells transfected with siXIAP; and (d) DFMO-treated cells transfected with siHuR. Apoptosis was measured by morphological analysis (middle) and ApoAlert annexin V staining (right) 4 h after treatment with TNF-α/CHX. Original magnification: x150. (C) Percentage of apoptotic cells as described in (B). *P<0.05 compared with no-TNF-α/CHX. +P<0.05 compared with DFMO treated cells that were transfected with C-siRNA and then treated with TNF- α/CHX for 4 h.