CXCR4, a Chemokine Receptor involved in organ vascularization, neuronal cell migration, and patterning of the central nervous system during development. It binds stromal cell-derived factor 1 (SDF1, also called PBFS) and mediates migration of resting leukocytes and is unique in homing hematopoietic progenitors to bone marrow. These properties suggest that CXCR4 is involved in tumor cell migration and local tumor invasion. It is also an HIV-1 fusion co-factor that allows HIV-1 invasion in diverse human cell types. Although this receptor was initially called Neuropeptide Y3 Receptor, it does not respond to neuropeptide Y. CXCR4 has two isoforms that are produced by alternative splicing.Synonyms: C-X-C chemokine receptor type 4, CXC-R4, CXCR-4, FB22, Fusin, HM89, LCR1, LESTR, Leukocyte-derived seven transmembrane domain receptor, NPYRL, SDF1 receptor, Stromal cell-derived factor 1 receptor