CXCL9 and chronic obstructive pulmonary disease: For this analysis we took advantage of relevant measures from a COPD serum profiling dataset (that is, CXCL9, CXCL10, CCL4, CCL5, CCL11, IL1beta and VEGF) used in a previous publication from our group [26] in order to test whether (1) serum cytokine protein levels were affected by disease and/or prolonged endurance training, and (2) if they were correlated with skeletal muscle gene expression.