PNPLA2 and steatosis: In our study, the concentration of serum-free fatty acid and the mRNA expression of cholesterol-binding regulatory binding protein (Srebp1c), fatty acid transporter (Fatp2, Fatp3, Fatp4), and fatty acid synthesis–related genes such as fatty acid synthase (Fas) in the BAMBI knockout group mice liver tissues were significantly higher than those of control group, while the expression of Atgl has no difference, suggesting that the increased fatty acid uptake and lipid synthesis in liver are important reasons for the aggravation of liver tissue steatosis in BAMBI AKO mice (Fig. 6G, H).