Carpagnano and colleagues hypothesized that ET-1, in pathological conditions (interstitial pulmonary disease and NSCLC), could be in part produced by airway epithelium itself [38,39], while the reason of an exaggerated ET-1 release in EBC in COPD with PAH is still unknown. The gene discussed is EDN1; the disease is Abnormal pulmonary interstitial morphology.