MMP9 and pulmonary fibrosis: Furthermore, ELISA was used to detect pulmonary fibrosis markers COL-1, COL-3, WNT, Vimentin, β-Catenin, Fibronectin, α-SMA, N-Cadherin, E-Cadherin, TWIST, CTGF, FGF2, PDGF-α, MMP2, MMP8, MMP9, MMP13, TIMP1, TGF-β, Smad2, and Smad3 expression levels (Fig. 2a-c).