Effect of ALDH2 on tunicamycin (TN)-induced apoptosis. (A) siRNA silencing of ALDH2 promoted TN-induced toxicity, evaluated by the MTT assay. (B) ALDH2 over-expression prevents cytotoxicity induced by TN, the effect of which was abrogated by LY294002. Cytotoxicity was evaluated by the MTT assay. (C) siRNA silencing of ALDH2 increased apoptosis in cardiomyocytes, determined by caspase-3 activity. (D) ALDH2 overexpression attenuated TN-induced elevation of caspase-3 activity, which was recovered by LY294002. The data (presented as percentages of control) are means ± SEM of three separate experiments. *p < 0.05 versus control; #p < 0.05 versus TN group; †p < 0.05 versus ALDH2 siRNA or Ad-ALDH2 + TN group.