COL1A1 and systemic sclerosis: In both IPF and SSc-ILD they express elevated MMP7, a peripheral blood IPF biomarker, elevated integrin αVβ6, a potent activator of latent TGF-β also implicated in matrix metalloproteinase expression (51), markers of epithelial-mesenchymal transition (such as COL1A1, CDH2, and FN1), and markers of cellular senescence (including CDKN2A(p16), CDKN1A(p21), and GDF15) (Supplemental Figure 12).