Effect of ALDH2 knockdown on ER stress in cardiomyocytes. (A) ALDH2 expression was inhibited in cardiomyocytes transfected with siRNA specific for ALDH2 (ALDH2-siRNA). The expression of GRP78 (B), p-eIF2α (C) and CHOP (D) was elevated by ALDH2 siRNA transfection compared with the tunicamycin (TN) treatment group and control. (E) p47phox subunit was promoted by ALDH2 knockdown compared with the TN treatment group and control. (F) p-Akt was decreased by ALDH2 knockdown compared with the TN treatment group and control. NAC was used as a positive control. Scr siRNA indicates scrambled siRNA used as control, which did not affect the ER stress markers. All values for a given protein expression were normalized to that of GAPDH. 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 + TN group.