SIRT3 and gastric cancer: In agreement with the literature showing SIRT3 deacetylates and activates MnSOD (11, 12), in gastric cancer cells, MnSOD activity was enhanced by SIRT3 overexpression (1.4-fold in AGS cells and 1.2-fold in SGC-7901 cells), but reduced by SIRT3 knockdown (50% in AGS cells and 65% in SGC-7901 cells) (Fig 5C and 5D), suggesting that SIRT3 may protect cells from oxidative stress-induced damage by rebalancing intracellular ROS through enhancing MnSOD activity in gastric cancer cells.