Purity >95% by SDS-PAGE, MW: 8.5 kDa. Stromal cell-derived factor-1 beta (SDF-1β), also called CXCL12b, is one of two SDF-1 splice variants made by a wide variety of cells upon stimulation by inflammatory cytokines such as tumor necrosis factors (TNF), interleukin 1 (IL-1), and lipopolysaccharide (LPS). SDF-1β signals through the G protein-coupled receptor CXCR4 to recruit activated leukocytes.