Purity ~95% (SDS-PAGE). Stem cell factor (SCF), also known as c-kit ligand (KL), mast cell growth factor (MGF), and steel factor (SLF), is a widely expressed 28-40kD type I transmembrane glycoprotein. It promotes the survival, differentiation, and mobilization of multiple cell types including myeloid, erythroid, megakaryocytic, lymphoid, germ cell, and melanocyte progenitors. SCF is a primary growth and activation factor for mast cells and eosinophils. Mature human SCF consists of a 189aa extracellular domain (ECD), a 23aa transmembrane segment, and a 36aa cytoplasmic tail. The ECD shows both N-linked and O-linked glycosylation. Proteolytic cleavage at two alternate sites in the extracellular juxtamembrane region releases a 25kD soluble molecule which is comparable to the only formproduced by Steel-dickie mutant mice. An alternatively spliced isoform of human SCF exists that lacks 28aa that encompass the primary proteolytic recognition site. Within the ECD of the long isoform (correspo