SMAD4 and renal fibrosis: This is supported by recent findings: SIRT1 physically interacts with SMAD4 and deacetylate SMAD4 in human endothelial cells, which results in the inhibition of TGF-β-induced EMT process and protecting against fibrosis; SIRT1 overexpression attenuate TGF-β-induced extracellular matrix expression in mesangial cells and then ameliorate renal fibrosis [25].