SHP2 is a protein tyrosine phosphatase (PTP) with two NH2-terminal SH2 domains, a PTP domain, a -COOH tail with two tyrosyl phosphorylation sites at Y546 and Y584, and an interposed proline-rich domain. SHP2 binds to activated KIT on tyrosine-568 in the juxtamembrane region, which also constitutes the docking site for a number of other signal transduction molecules, such as SFKs, Csk homologous kinase (CHK), CBL, LNK and Adapter protein with PH and SH2 domains (APS) (Kozlowski et al. 1998, Price et al. 1997, Gueller et al. 2008).