ATF3 and obesity due to melanocortin 4 receptor deficiency: Regarding liver metabolism: increased Atf3 expression has been associated with hepatic steatosis and impaired glucose homeostasis in ZDF rats (17) and Atf3-overexpressing mice (18, 19), but other studies exhibit protective effects of liver-specific Atf3 on hepatic lipid metabolism and atherosclerosis in both human and mouse models of obesity and metabolic dysfunction–associated fatty liver disease (19, 20, 21).