The TGF-β1 stimulated increase of both gene and protein levels of type I collagen and fibronectin in both fibroblast types and of type III collagen in pulmonary fibroblasts correlates with previous findings in SSc, fibrotic pulmonary, and healthy dermal and pulmonary fibroblasts22–26,28,29,45,46. Here, TGFB1 is linked to systemic sclerosis.