TGFB1 and diabetic kidney disease: In this regard, kidney fibrosis is a key contributor to DKD progression and TGF-β1-induced KLF4 promoter hypermethylation and KLF4 downregulation in cultured human tubular cells was attenuated by decitabine [79], which also prevented high glucose-induced suppression of regulator of calcineurin 1 (RCAN1) expression in cultured podocytes [80].