CXCR2 and neoplasm: Neutrophil-attracting chemokines, such as CXCL1, CXCL2, or CXCL8, are induced in hypoxic tumor tissue, through the activation of hypoxia-inducible factor 1 (HIF-1α or β) [46,57,71], and support neutrophil migration to the tumor site via CXCR1 and CXCR2 receptors [72].