CXCR2 and chronic obstructive pulmonary disease: After serine phosphorylation in the p53 protein, p53 binds to PAI-1 to promote PAI-1 expression, leading to the increase of CXCL1, CXCL2 and CXCR2 in COPD patients (Tiwari et al., 2016), which could induce the influx of neutrophils to infection site.