Purity ~98% (SDS-PAGE, HPLC). Stem Cell Factor (SCF) is a hematopoietic growth factor that exerts its activity at the early stages of hematopoiesis. SCF stimulates the proliferation of myeloid, erythroid, and lymphoid progenitors in bone marrow cultures. Source: Recombinant protein corresponding to 165aa residues from human Stem Cell Factor, expressed in E. coli. Molecular Weight: ~18.9kD Biological Activity: The ED50, as determined by the dose-dependent stimulation of the proliferation of human TF-1 cells, is 5x10e5units/mg. Endotoxin: <0.1ng/ug