Tyrosine-protein kinase Kit, also known as proto-oncogene c-Kit or CD117 or Mast/stem cell growth factor receptor (SCFR), is a receptor tyrosine kinase protein that in humans is encoded by the KIT gene. Activating mutations in this gene are associated with gastrointestinal stromal tumors, testicular seminoma, mast cell disease, melanoma, acute myeloid leukemia, while inactivating mutations are associated with the genetic defect piebaldism.