PPBP and neoplasm: CXCR2, the CXC receptor expressed by neutrophils, can bind with its ligand chemokine family (CXCL1, CXCL2, CXCL3, CXCL5, CXCL7, and CXCL8) to recruit neutrophils to the TME and participate in the mobilization of tumour-associated neutrophils (81, 82).