Stem Cell Factor is also known as SCF, kit-ligand, KL, steel factor, KITLG, FPH2, KL-1, Kitl, MGF, SCF, SF, or SHEP7, and is a cytokine that binds to the c-Kit receptor (CD117). Stem cell factors perform their biological functions by binding to and activating the receptor tyrosine kinase c-Kit. The human SCF gene encodes for a 273 amino acid transmembrane protein, which contains a 25 amino acid N-terminal signal sequence, a 189 amino acid extracellular domain, a 23 amino acid transmembrane domain, and a 36 amino acid cytoplasmic domain. Stem cell factor (SCF) has been shown to stimulate the proliferation of myeloid, erythroid, and lymphoid progenitor cells in bone marrow culture and has been shown to work synergically with colony-stimulating factors.