SDF-1 is a CXC chemokine that has several distinguishing features. It widely expressed and has a broad range of actions, affecting T cell chemotaxis, В cell chemotaxis. В cell development. CD34+ stem cell migration, and neural development, as well as the development and vascularization of various other tissues. SDF-1 appears to be particularly important for basal trafficking of cells, for instance naive T cell traffic through lymph nodes, rather than the trafficking of effector leukocytes to inflammatory lesions. SDF-1 is highly conserved between mouse and human, and binds to the chemokine receptor CXCR4. SDF-1 is able to inhibit T-tropic HIV-1 entry into CXCR4-bearing cell lines, and SDF-1 expression may have an important bearing on AIDS pathogenesis, since a polymorphism in the human SDF-1 gene affects the onset of AIDS.