TGFB1 and systemic sclerosis: On the other hand, in the sclerotic phase SSc dermal fibroblasts are constitutively activated with a pro-fibrotic phenotype similar to that of normal fibroblasts treated with TGF-β1, even though the expression of TGF-β is weak or undetectable in the skin [97], suggesting that SSc fibroblasts possess a self-activation system at least partially via autocrine TGF-β signaling.