Stromal cell Derived Growth Factor-1 beta (SDF-1 beta ), also called CXCL12, is one of two splice variants made by a wide variety of cells when stimulated by inflammatory cytokines such as, TNF, IL-1 or LPS. SDF-1 beta signals through the G Protein-couple receptor, CXCR4, to recruit activated leukocytes. SDF-1 beta shares 100% identity to feline SDF-1 beta. Recombinant SDF-1 beta is a non-glycosylated Protein, containing 72 amino acids, with a molecular weight of 8.5 kDa.