STAT3 and infection: Infection with the hepatitis B virus (HBV) is a leading cause of hepatocellular carcinoma (HCC) 75, and HBV promotes the migration of liver cancer cells by downregulating miR-340-5p to induce STAT3 overexpression, indicating that STAT3 plays a key role in regulating cell migration in HBV-HCC involving miR-340-5p 76.