CXCR2 and chronic obstructive pulmonary disease: The CXCLs/CXCR2 axis plays a vital role in apoptosis, epithelial-to-mesenchymal transition, and cell proliferation in lung cancer (Cheng et al., 2021), and unresolving neutrophilic airway inflammation of patients with COPD and severe asthma (Uddin et al., 2010; Simpson et al., 2013; Uddin et al., 2019).