SMAD2 and Myocardial fibrosis: Specifically, Upon binding with TGF-β1 receptor on the surface of myocardial fibroblasts, TGF-β1 stimulates phosphorylation of downstream Smads protein (mainly Smad2/3) and translocation into the nucleus, induces myocardial fibroblasts proliferation, phenotypic transformation, and collagen synthesis, and ultimately promotes extracellular matrix formation and myocardial fibrosis (Petrov et al., 2002; Shen et al., 2011; Ma et al., 2018).