Until recently the CXCR-7 was an “orphan” receptor with its endogenous ligand unknown. This receptor is encoded by the CXCR7/RDC-1 gene which was mapped to mouse chromosome 1 and human chromosome2. Homology has been shown with the viral gene ORF74 suggesting the receptor might signal without the binding of a ligand. Currently it is known that the chemokines CXCL12 and CXCL11 bind to CXCR-7.nCXCR-7 is tightly linked to the regulation of B cell development and differentiation indicating it might have a role in the formation of B memory cells4. CXCR-7 was also found to be associated with tumors where its levels are elevated in many tumor cell lines such as endothelial cells, fetal liver cells and placenta cells5. Despite this suggested role, there is growing evidence that this receptor does not function as a regular GPCR6.