Fig. 4. Enhancement of AKT activity by AKT-CA vector transfection decreased the cytotoxicity induced by capsaicin. (A) After the cells were transfected with pcDNA3 or AKT-CA expression vector, the cells were treated with capsaicin for 24 h. Cytotoxicity was determined by MTS assay. The results (mean ± SEM) were from three independent experiments. (B) After the cells were transfected with a pcDNA3 or AKT-CA expression vector, the cells were treated with capsaicin (50 μM) for 24, 48, and 72 h, after which living cells were determined by trypan blue exclusion assay. *p < 0.05, **p < 0.01 using Student's t-test for comparison between the cells treated with capsaicin in AKT-CA or pcDNA3 vector-transfected cells. (C) Cells were pretreated with LY294002 (5 μM) for 1 h and then co-treated with various concentration of capsaicin for 24 h. Cytotoxicity was determined by MTS assay. **p < 0.01 using Student's t-test for comparison between the cells pretreated with or without LY294002 in capsaicin exposed cells. (D) Cells were treated with capsaicin (25 μM) and/or LY294002 (5, 10 μM) for 1–3 days, after which living cells were determined by MTS assay. **p < 0.01 using Student's t-test for comparison between cells treated with capsaicin alone or with a capsaicin and LY294002 combination.