CXCR4 is a receptor for the C-X-C chemokine SDF-1 (Stromal Cell-Derived Factor 1). It is involved in haematopoiesis and cardiac ventricular septum formation, and plays an essential role in vascularization of the gastrointestinal tract, cerebellar development and survival of hippocampal-neuron of central nerve system. CXCR4 also acts as a primary receptor for some HIV-2 isolates and as a co-receptor with CD4 for HIV-1 X4 viruses.