CXCR4 is a chemokine receptor that belongs to the G protein-coupled receptor family. It is activated by a small cytokine, CXCL12, also known as stromal cell derived factor 1 (SDF-1). The main function of CXCR4 is the mediation of the homing of progenitor cells in the bone marrow and their recruitment to sites of injury . The protein has 7 transmembrane regions and is located on the cell surface. It acts with the CD4 protein to support HIV entry into cells and is also highly expressed in breast cancer cells. More recently, CXCR4 has been studied, as a potential therapeutic target, in the context of autoimmune diseases as well as cancer, as the receptor is involved in the regulation of migration, proliferation, and survival of cancer cells.
