FMS-related tyrosine kinase 3 (FLT3, also called Flk2), a member of the type III receptor tyrosine kinase family that includes c-Kit, PDGF and M-CSF receptors, is expressed on early hematopoietic progenitor cells, and supports growth and differentiation within the hematopoietic system (1,2). FLT3 is activated after binding with its ligand FL, which results in a cascade of tyrosine autophosphorylation and tyrosine phosphorylation of downstream cellular targets (3). The p85 subunit of PI3 kinase, SHP2, GRB2 and Shc are associated with FLT3 after FL stimulation (4