Stromal cell–derived factor-1 (SDF-1), also called CXCL12 or CXC motif chemokine 12, is a small cytokine with chemotactic activity. SDF-1α and SDF-1β are generated by alternate splicing of the same gene. 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.

, 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

and

, as well as for mesenchymal stem cells

. SDF-1 is implicated in neuronal migration, neural development, brain inflammation, and tumor growth

.

cytokines are suitable for a wide variety of cell culture applications. They are sterile-filtered prior to lyophilization. Generally, endotoxin levels are <0.1 ng/μg (<1 EU/μg), and purities are >95%. The biological activity is tested in appropriate bioassays.