FOXOs also have beneficial effects in the context of diabetes, as FOXO-dependent transcription of antioxidant enzymes may counteract oxidative stress-induced cellular damage [52], which agrees with our findings that overall ROS level is lower in liver homogenates of db/db mice compared to those of c57, though expression of Cu-ZnSOD and catalase in the liver of ob/ob or db/db mice is similar to that of c57 mice. Here, CAT is linked to diabetes mellitus.