NRG4 and fatty liver disease: This is thought to be primarily related to the thermogenic capacity of BAT and its secretion of regulatory factors, such as neuregulin 4 (Nrg4), which exerts its effects by activating epidermal growth factor receptor 3 (ErbB3) and epidermal growth factor receptor (ErbB4) signaling pathways in hepatocytes, helping counteract diet-induced hepatic steatosis (37).