Feline McDonough Sarcoma-like tyrosine kinase (FLT3) is a member of the class III tyrosine kinase receptor family. Ligand binding induces conformational changes in FLT3 receptor, which facilitates its dimerization. This process exposes phosphate acceptor sites in the catalytic domain of FLT3. Subsequently, FLT3 autophosphorylates at these sites. Several phosphorylation sites have been reported and there may be more modifications required to fully activate FLT3 (Heiss et al. 2006, Masson et al. 2009, Razumovskaya et al. 2009). Experiments confirming this event were performed in mouse cells.