All 4 slides from non-COPD patients contained high levels of EPAS1, and 3 of 5 slides from the COPD patients contained low levels of EPAS1 as shown in S7 Fig., so that a statistically significant difference in EPAS1 protein levels was observed between the two groups (p-value = 0.03). This evidence concerns the gene EPAS1 and chronic obstructive pulmonary disease.