TGFB1 and chronic kidney disease: It is widely known that CDKI p21Cip1/WAF1 (p21) plays a key role in MC hypertrophy and glomerular hypertrophy leading to chronic renal diseases including DN [1, 3, 4, 7, 8, 29, 30]; p21 is the target gene of multiple cytokines and growth factors including TGF-β1 [5, 8, 19].