SMAD2 and renal fibrosis: Diabetic kidney injury usually results in renal fibrosis, which is regulated by TGF‐β1.[33] Our results showed that HGL treatment increased the expression of TGF‐β1 and the phosphorylation of Smad2 and Smad3 as well as the expression of α‐SMA and Vimentin, but decreased the expression of E‐Cad in HK‐2 cells.