TGFB1 and pulmonary arterial hypertension: Direct blockade of TGF-β signalling is a major therapeutic challenge due to its ubiquitous nature and localized signalling effects: targeting the pathologic activation of TGF-β, such as in patients with Schistosoma-associated PAH or with scleroderma at risk for developing scleroderma-associated PAH, holds promise as a potentially safer approach.