TGFB1 and diabetic kidney disease: A number of studies also showed that in renal fibrosis caused by a unilateral ureteral obstruction (UUO) or DKD, the level of SnoN protein decreased gradually, while the hyperactivity of TGF-β1/Smad signaling pathway was persistent, accompanied by the phenotypic changes of RETCs and the deposition of ECM in the interstitium [17–19].