TGFB1 and systemic sclerosis: Distler et al. showed that the treatment of cultured fibroblasts from both SSc patients and healthy controls with imatinib led to a dose-dependent inhibition of the synthesis of collagen Ia1, collagen Ia2, and fibronectin-1 when the fibroblasts were stimulated with TGF-β, PDGF, or left in their baseline state.