GDF2 and Hepatic fibrosis: As an example, aberrant BMP9 signaling has been reported to induce the activation of hepatic stellate cells and promote the progression of liver fibrosis (Breitkopf-Heinlein et al., 2017; Li et al., 2018), but to hinder cardiac fibroblast activation and delay cardiac remodeling and myocardial fibrosis (Morine et al., 2017; Morine et al., 2018), indicating that the response of BMP9 to fibroblast activation varies with cell types.