STAT3 and chronic obstructive pulmonary disease: The presence of activated EGFR in the lungs of smokers could explain the high expression of phosphorylated STAT3 found in COPD (36), which would sustain the IL-6 roles in the acute phase response, chronic inflammation, autoimmunity, endothelial cell dysfunction, and cancer progression even in the presence of high levels of SOCS3 (36, 43).