Cells from Booreana mice are resistant to transformation by AML oncogenes in vivo. (A) Percentage of leukemia-free surviving irradiated recipient mice (n = 8) receiving AML1-ETO9a– and MLL-AF9–expressing WT and Booreana donor cells. Only the former succumb to a myeloid leukemia with (B) increased numbers of GFP⁺ cells in their peripheral blood. Cells in the peripheral blood of AML1-ETO9a–expressing WT donor mice exhibit a Kit⁺ phenotype, whereas those of MLL-AF9–expressing WT donor mice exhibit a Kit⁺CD11b⁺Gr-1⁺ phenotype, reminiscent of a monocytic leukemia.