IDH2 and Hepatic steatosis: In addition, IDH2 expression in the liver is minor relative to that in the BAT (Fig. S4), and thus, the liver steatosis at 4 weeks of HFD likely develops at least partially as a secondary effect from defective ROS regulation in the BAT that leads to a deficit in whole-body expenditure, resulting in increased levels of excess fat deposition in the liver and compromised liver function by 16 weeks of HFD.