Stromal Cell Derived Factor 1 beta, Recombinant, Human (SDF1b, CXCL12b, Pre-B Cell Growth-stimulating Factor, PBSF, hIRH, Chemokine (C-X-C Motif) Ligand 12b, TPAR1, SCYB12, TLSF-b)

SDF-1 (stromal cell-derived factor-1) is small cytokine belonging to the chemokine family that is officially designated Chemokine (C-X-C motif) ligand 12 (CXCL12). Stromal cell-derived factors 1-alpha and 1-beta are small cytokines that belong to the intercrine family, members of which activate leukocytes and are often induced by proinflammatory stimuli such as lipopolysaccharide, TNF, or IL1. The intercrines are characterized by the presence of 4 conserved cysteines which form 2 disulfide bonds. They can be classified into 2 subfamilies. In the CC subfamily, which includes beta chemokine, the cysteine residues are adjacent to each other. In the CXC subfamily, which includes alpha chemokine, they are separated by an intervening amino acid. The SDF1 proteins belong to the latter group. SDF-1 is produced in two forms, SDF-1a/CXCL12a and SDF-1b/CXCL12b, by alternate splicing of the same gene.[2] Chemokines are characterized by the presence of four conserved cysteines, which form two disulfide bonds. The CXCL12 proteins belong to the group of CXC chemokines, whose initial pair of cysteines are separated by one intervening amino acid.\n\nCXCL12 is strongly chemotactic for lymphocytes.[3][4][5][6] During embryogenesis it directs the migration of hematopoietic cells from foetal liver to bone marrow and the formation of large blood vessels. Mice which were knocked-out for CXCL12 gene were lethal before the birth or within just 1 hour of life. In adulthood CXCL12 plays an important role in angiogenesis by recruiting endothelial progenitor cells (EPC) from the bone morrow through a CXCR4 dependent mechanism.[7] It is this function of CXCL12 that makes it a very important factor in carcinogenesis and the neovascularisation linked to tumor progression. [8] CXCL12 was shown to be expressed in many tissues in mice (including brain, thymus, heart, lung, liver, kidney, spleen and bone marrow).\n\nThe receptor for this chemokine is CXCR4, which was previously called fusin.[9] This CXCL12-CXCR4 interaction used to be considered exclusive (unlike for other chemokines and their receptors), but recently it was suggested that CXCL12 is also bound by CXCR7 receptor.[10][11] The gene for CXCL12 is located on human chromosome 10.[12] In human and mouse both CXCL12 and CXCR4 show high identity of sequence: 99% and 90%, respectively.\n\nSource: \nRecombinant corresponding to 74aa from human SDF-1b expressed in E. coli.\n\nMolecular Weight: \n~8.7kD\n\nBiological Activity: \nED50 range=1000-2000 g/ml, determined by the dose dependent calcium influx measured in FURA-2 labeled Reh cells. Optimal concentration for individual application should be determined by a dose response assay. \n\nEndotoxin: (same/less than) 0.1ng/ug\n\nStorage and Stability:\nLyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

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