Irrespective of the genotype of the donor stem/progenitor cells, AML developed in all mice reconstituted with MLL-AF9 or MLL-ENL virus-infected cells, most needing to be euthanized within a period of 30–65 days (Figures 1b and c and Supplementary Figure S1a). The gene discussed is MLLT3; the disease is acute myeloid leukemia.