FLT3 and myeloproliferative neoplasm: The vast majority of wild type mice have normal bone marrow, the majority of Flt3+/ITD mice develop a myeloid neoplasm (primarily MPN), the predominant phenotype in the Wt1+/R394W mice evaluated is MDS, and the majority of Flt3+/ITD/Wt1+/R394W mice develop an MDS/MPN.