TGFB1 and pulmonary arterial hypertension: Soluble guanylate cyclase activators inhibited the release of TGF-β-induced extracellular matrix proteins from primary dermal fibroblasts obtained from both normal volunteers and SSc subjects, and dermal fibrosis was reduced in the bleomycin skin fibrosis model of SSc.56,57 Riociguat has been shown in large randomized controlled clinical trials to be effective in patients with different forms of pulmonary hypertension, including patients with SSc-related PAH,58 and is now in a trial for the skin thickening of SSc.