SERPINH1 and pulmonary fibrosis: Exogenous NO induced the expression of HSP47, collagen type 1, TGF-β1, and phosphorylated SMAD-2 in human fetal lung fibroblast MRC-5 cells, suggesting that NO promotes the progression of pulmonary fibrosis via the TGF-β1/SMAD signaling cascade and increases HSP47 expression in pulmonary fibroblasts [30,31].