PAI-1 is, in fact, a prominent member of the activated fibroblast gene signature in bleomycin-induced pulmonary fibrosis as well as in serum-stimulated human fibroblasts, and the small-molecule PAI-1 inhibitor SK-216 mitigates TGF-β1-induced myofibroblast differentiation and lung fibrosis [41,193,194]. This evidence concerns the gene SERPINE1 and pulmonary fibrosis.