EDN1 and idiopathic pulmonary fibrosis: A large number of cytokines are involved in the thogenesis of IPF including transforming growth factor-β (TGF-β)  (8), tumour necrosis factor-α (TNF-α) (9), insulin-like growth factor-1 (IGF-1) (10), endothelin-1 (ET-1) (11), interleukin (IL)-1, IL-7 (12), IL-8 (13), IL-10  (8) and IL-12 (14).