To determine if TF-1 cells are also susceptible to transformation by active mutants of Flt3 associated with AML, we transduced TF-1 cells with retroviral vectors for wild-type Flt3, a Flt3-ITD mutant identical to the one found in MV4-11 cells, and an active Flt3 point mutant, D835Y. The gene discussed is FLT3; the disease is acute myeloid leukemia.