CXCL1 and chronic obstructive pulmonary disease: The inflammation in COPD mirrors that profile of SASP mediators, with increased cytokines (IL-1β, IL-6, TNF-α), chemokines (CCL2, CXCL1, CXCL8), proteases (MMP-2, MMP-9), and growth factors (TGF-β, PAI-1).