Cisplatin enhances AAV-mediated TRAIL expression and apoptosis in KB cells. KB cells pre-treated or post-treated with cisplatin were transducted with AAV/TRAIL for 72 h, the cells were harvested and TRAIL expression was analyzed by (A) ELISA assay and (B) Western blot assay. Purified rsTRAIL was used as a standard. The cells pre-treated with cisplatin (200 ng/mL for 2 h) and apoptosis was detected by MTT assay (C) and (D) Western blot analysis for the activation of caspase-8 and -3 in KB cells. Densitometric analysis showing change in optical density of TRAIL, cleaved caspase-3 and -8 bands. GAPDH expression was used as adjustment. Values are mean of three independent experiments with error bar representing standard deviation of the mean. **P < 0.01 compared to the values obtained with the equivalent dose of AAV/TRAIL alone. ##P < 0.01 compared to the sum effect of AAV/TRAIL and cisplatin.