New insights into BMP9 signaling in liver diseases.

Bone morphogenetic protein 9 (BMP9) is a recently discovered cytokine mainly secreted by the liver and is a member of the transforming growth factor β (TGF-β) superfamily. In recent years, an increasing number of studies have shown that BMP9 is associated with liver diseases, including nonalcoholic fatty liver disease (NAFLD), liver fibrosis and hepatocellular carcinoma (HCC), and BMP9 signaling may play dual roles in liver diseases. In this review, we mainly summarized and discussed the roles and potential mechanisms of BMP9 signaling in NAFLD, liver fibrosis and HCC. Specifically, this article will provide a better understanding of BMP9 signaling and new clues for the treatment of liver diseases.