SMAD3 and pulmonary fibrosis: VEGF has been shown to inhibit renal fibrosis and EMT, which may be related to VEGF-blocking, TGF-β-induced Smad3 phosphorylation and upregulating Smad7 expression.32 In pulmonary fibrosis studies, the function of VEGF is controversial; some authors believe that VEGF can promote revascularization and accelerate pulmonary fibrosis,33 while others believe that VEGF can maintain the normal function of tissue structure to resist pulmonary fibrosis.