SMAD3 and renal fibrosis: Therefore, in this article, we could know that KXL decoction played an important role in alleviating renal fibrosis by inhibiting the expression of TGF-β1, Smad2, Smad3, Collagen I, Collagen III, and CTGF and promoting the expression of Smad7, thereby reducing the occurrence and development of renal fibrosis.