Stromal cell–derived factor-1 (SDF-1), also called CXCL12 or CXC motif chemokine 12, is a small cytokine with chemotactic activity. The sequence of SDF-1 is highly conserved among the species. Mouse SDF-1 differs only in one amino acid from human SDF-1 and therefore shows cross-reactivity. SDF-1 binds to the G-protein-coupled seven-transmembrane receptor CXCR4 and induces a rapid and transient rise in the level of intracellular calcium ions and chemotaxis. CXCR7 has been identified as another seven-transmembrane receptor for SDF-1, suggesting a role for SDF-1 in several aspects of tumorigenesis.
In vitro , SDF-1 is a potent chemoattractant for T lymphocytes and monocytes, but not for neutrophils. Furthermore SDF-1 acts as a chemoattractant for CD34
+ human hematopoietic progenitor cells
in vivo and
in vitro , as well as for mesenchymal stem cells
in vitro . SDF-1 is implicated in neuronal migration, neural development, brain inflammation, and tumor growth
in vivo .