In renal and liver fibrosis, binding of TGF-β to its corresponding receptors results in SMAD3 (Mothers against decapentaplegic homolog 3) activation, leading to increased expression of plasminogen activator inhibitor-1 (PAI1, also known as endothelial plasminogen activator inhibitor (serpin E1))16,17. Here, SMAD3 is linked to Hepatic fibrosis.