TGFB1 and renal fibrosis: Fibroblast growth factor 21 (FGF21) attenuated nuclear translocation of Smad2/3 by inhibiting renal activity of its conjugated protein p53, which carries Smad2/3 into the nucleus, thus negatively regulating the TGF‐β/Smad2/3‐mediated EMT process and preventing renal fibrosis.139