EPAS1 (endothelial periodic acid‐Schiff domain protein 1), also known as HIF2‐alpha, is expressed in type II pneumocytes and pulmonary endothelial cells.63 Several studies evaluating the role of EPAS1 in lung cancer demonstrated that its activity is puzzling and ambiguous.64, 65 Collectively, the literature suggests inhibition of overexpressed EPAS1 in lung cancer might have beneficial effects but reductions below a critical threshold favor tumorigenesis and are associated with poor prognosis. The gene discussed is EPAS1; the disease is lung carcinoma.