JAK2 and fatty liver disease: Previous studies have shown that leptin knockout mice (ob/ob) exhibited reduction of the leptin receptor and blocking of the signal transduction of JAK2/STAT3.44 However, in this study, high-fructose-induced hepatic steatosis mice showed that the hepatic leptin receptor was significantly increased, while JAK2, p-JAK2 and p-STAT3 were significantly decreased, which means that the JAK2/STAT3 pathway was blocked.