C-kit (CD117, 145kDa) functions as a tyrosine kinase receptor which becomes activated upon binding of its ligand SCF (stem-cell factor), the C-kit gene encodes the human homolog of the proto-oncogene c-kit. which was first identified as the cellular homolog of the feline sarcoma viral oncogene v-kit. KIT is a type 3 transmembrane receptor for MGF (mast cell growth factor). Mutations in KIT are associated with gastrointestinal stromal tumors, mast cell disease, acute myelogenous lukemia, and piebaldism.