To test whether EPAS1 protein abundance concordantly changes with EPAS1 gene expression levels in lung tissues of COPD patients, we stained lung tissue blocks from 5 COPD patients and 4 non-COPD patients using a polyclonal anti-EPAS1 antibody (NB10-122; Novus Biologicals, CO, USA) and categorized EPAS1 abundance. This evidence concerns the gene EPAS1 and chronic obstructive pulmonary disease.