This finding was consistent with other studies in which inhibition of Smad3 with SIS3 (a Smad3 inhibitor to block Smad3 DNA binding and phosphorylation) and GQ5 (a small compound isolated from the dried resin of Toxicodendron vernicifluum that blocks the binding of Smad3 to TGF-β type I receptor) attenuates renal fibrosis [30, 31]. Here, SMAD3 is linked to renal fibrosis.