GREM1 and idiopathic pulmonary fibrosis: Many experimental evidences suggest that Gremlin could be an important promoter of fibrosis in different pathologies, including liver fibrosis, lung diseases (particularly pulmonary hypertension and idiopathic pulmonary fibrosis), myocardial fibrosis, and chronic pancreatitis (Khokha et al., 2003; Mueller et al., 2013; Brazil, 2015; Mezzano et al., 2018).