EDN1 and pulmonary fibrosis: Numerous cytokines have been implicated in the pathogenesis of lung fibrosis, including transforming growth factor-β (TGF-β), tumour necrosis factor-α (TNF-α), platelet- derived growth factor (PDGF), insulin-like growth factor-1 (IGF-1), endothelin-1 (ET-1) and the interleukins, (IL)-1 and IL-8.