The c-Kit proto-oncogene has been identified as a member of the receptor tyrosine kinase family and more specifically has been shown to be closely related to the platelet derived growth factor receptor (PDGFR). c-Kit, the normal cellular homolog of the HZ4-feline sarcoma virus transforming gene v-Kit, encodes a transmembrane receptor with a molecular weight of 145- 160 kDa. c-Kit has also been show to be identical with the product of the W locus in mice and as such is integral to the development of mast cells and hematopoiesis. The ligand for the c-Kit receptor (KL) has been identified and shown to be encoded at the murine steel (SI) locus. Two sites on c-Kit are able to bind SH2(CHK), the Tyr 568/570 diphosphorylated sequence and the monophosphorylated Tyr 721 sequence.Synonyms: KIT, Mast/stem cell growth factor receptor, Proto-Oncogene Tyrosine-Protein Kinase, SCFR