To link EGFR activation with collagen production, we performed immunofluorescence imaging of pEGFR and procollagen I. From low power, pEGFR and pro-collagen co-stain SSc fibrotic dermis (Fig. 1h) and this was absent in healthy control skin as well as with the pEGFR isotype antibody (Fig. S1b). This evidence concerns the gene EGFR and systemic sclerosis.