CXC chemokine receptors are integral membrane proteins (GPCR-A2) that specifically bind and respond to cytokines of the CXC chemokine family. CXCR1 and CXCR2 (IL8R-α and IL8R–β respectively) are closely related receptors that recognize CXC chemokines that possess an E-L-R amino acid motif immediately adjacent to their CXC motif; they are both expressed on the surface of neutrophils in mammals. While CXCR3 is expressed predominantly on T lymphocytes, the CXCR4 receptor has a wide cellular distribution, with expression on most immature and mature hematopoietic cell types.
 Chemokine receptors and their role in inflammation and infectious diseases. Murdoch C., Finn A. Blood 2000, 95, 3032–3043