HNF4A and steatosis: In addition, Calo et al. (44) revealed a new role for miR-21 in hepatocytes in promoting hepatic insulin resistance and steatosis in diet-induced obese mice through regulation of forkhead box protein O1 (Foxo1), insulin induced gene 2 (Insig2), STAT3 and Hepatocyte nuclear factor 4 alpha (HNF4-α).