Description
Stem cell factor (SCF), also known as KIT ligand, MGF and steel factor, is a type I transmembrane glycoprotein and hematopoietic growth factor that exerts its activity at the early stages of hematopoiesis (1). It is produced by the Sertoli cells and is involved in the local regulation of spermatogenesis and liver regeneration (2). Non-covalent forms of SCF interact with the receptor tyrosone kinase c-Kit (CD117) to trigger receptor dimerization and signaling (3). The activation of c-Kit subsequently activates multiple signaling cascades, including the RAS/ERK, PI3-Kinase, Src kinase and JAK/STAT pathways (4). SCF, in conjunction with IL-31, may play a significant role in airway remodeling by promoting the recruitment of bone marrow-derived fibroblast precursors into the lung (5). It also mediates cell to cell adhesion, again by acting synergistically with other cytokines. A soluble form of SCF is produced by proteolytic processing of the molecule in the extracellular domain (6). Human SCF manifests low activity on murine cells, while murine and rat SCF are fully active on human cells