A study on renal and pulmonary fibrosis found that NF-κB is the upstream regulatory gene of TGF-β1, whose initiation can induce an increase in TGF-β1 protein expression and then promote the expression of Smad3 protein to promote fibrosis.27 28 There is also a negative feedback regulation mechanism. This evidence concerns the gene NFKB1 and pulmonary fibrosis.