DLL1 and chronic obstructive pulmonary disease: Levels of OPG, PTX3, AXL, ALCAM, sCD163, CD147, CatS and DLL1 were significantly higher in serum from COPD patients compared to the complete LC patient-cohort regardless of COPD, after multivariate analyses of covariance (corrected for age, gender and pack-years) and correction for multiple testing.