Notably, serum levels of CXCR2 ligands did not grossly differ between tumor-bearing and tumor-free mice in these early disease states which might be due to cytokine buffering activity of erythrocytes.24 Consequently, circulating neutrophils might encounter higher local concentrations of these tumor-released chemokines when passing the tumor microenvironment, where these immune cells are thought to be retained for an extended period of time.25 26. This evidence concerns the gene CXCR2 and neoplasm.