TGFB1 and systemic sclerosis: Alternatively, or in addition, the experimental induction of PTP4A1 by TGFβ in NHDF lines suggests that increased levels of TGFβ in the pro-fibrotic milieu of SSc skin, together with enhanced endogenous TGFβ sensitivity of SSc fibroblasts, might underlie the overexpression of PTP4A1 in early SSc skin stages and SSc fibroblasts5, 46, 47.