SMAD7 and renal fibrosis: Further studies revealed that inhibition of renal fibrosis in CHYS-treated diabetic rats was associated with inhibition of TGF-β1/Smad3 signaling as demonstrated by upregulation of Smad7 but downregulation of TGF-β1, TGF-β receptors, activation of Smad3, and expression of miRNA-21.