Given that SSc fibroblasts are constitutively activated by autocrine stimulation of transforming growth factor- β (TGF-β), a potent inducer of ET-1, and produces an excessive amount of ET-1 [4,9,31,37,38], autocrine ET-1 appears to be involved in the self-activation system in SSc fibroblasts. Here, TGFB1 is linked to systemic sclerosis.