LTBP4 and chronic obstructive pulmonary disease: Among the most up-regulated were NFKBIB, LTBP4, EGLN2, and TGFB1, all of which have been previously associated with an increased risk for COPD in GWAS and/or candidate gene studies (Table S1 in File S1), and EGLN2 has been clearly identified at a risk locus by a recent GWAS publication [10].