Hematopoiesis is governed by a number of cytokines that promote the survival, proliferation, and differentiation of hematopoietic stem cells and progenitor cells. Stem cell factor (SCF; also known as kit ligand, mast cell growth factor, or steel factor) is a hematopoietic cytokine that triggers its biologic effects by binding to its receptor, c-kit.
It is a glycoprotein that plays a key role in hematopoiesis acting both as a positive and negative regulator, often in synergy with other cytokines. The concentration of SCF in normal human serum is, on average, 3.3 ng/mL.
SCF is a member of the helical cytokine structural superfamily characterized by a double-crossover four-helix bundle topology. It is normally found in both soluble and transmembrane forms.