Purity >95% as determined by SDS-PAGE. Stromal cell-derived factor-1 beta (SDF-1b), 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 TNF, IL-1, and LPS. SDF-1b signals through the G protein-coupled receptor CXCR4 to recruit activated leukocytes.