To investigate the cooperative nature of Flt3 and Dnmt3a mutations in leukemogenesis, Meyer et al52 crossed the mouse lines to a myeloproliferative neoplasm model (Flt3ITD/ITD; Dnmt3afl/fl) and acute myeloid leukemia (AML) model (Flt3ITD/ITD; Dnmt3afl/fl MxCre). Here, FLT3 is linked to acute myeloid leukemia.