To test this hypothesis, we first generated primary AML by retrovirus mediated expression of the potent fusion oncogene MLL-ENL, and next transplanted the resulting GFP-positive leukemic cells into sub-lethally irradiated 12–15 weeks old Cebpafl/fl and Cebpafl/fl;CD2iCre secondary recipients (Figure 5A). The gene discussed is MLLT1; the disease is acute myeloid leukemia.