COL1A1 and systemic sclerosis: We found that AP (WNT2, SFRP2 and THY1), ECM (FN1, COL1A1 and POSTN) and TGFβ pathway (CTGF/CCN2 and SERPINE1) gene expression levels were significantly higher in the SSc samples than in the healthy control samples (Figure 8B; Figure S6A).