CD117 Antigen, also called KIT or C-kit receptor, is a cytokine receptor expressed on the surface of hematopoietic stem cells as well as other cell types. It has a tyrosine-protein kinase activity. Binding of the ligands leads to the autophosphorylation of KIT and its association with substrates such as phosphatidylinositol 3-kinase (Pi3K). Mutations in this gene are associated with gastrointestinal stromal tumors, mast cell disease, acute myelogenous leukemia, and piebaldism.