MEPs deficient for p53 and expressing oncogenic Nras are transformed to AML-initiating cells. Control and Nras^G12D/+p53^−/− mice were treated with pI-pC and euthanized on day 12 as described in “Materials and methods.” GMPs and MEPs were isolated from Nras^G12D/+p53^−/− bone marrow and transplanted to lethally irradiated mice as described in Table 1. Control recipients were transplanted with 2.5 × 10⁵ total bone marrow cells (CD45.2⁺) from control mice and the same number of congenic bone marrow cells (CD45.1⁺). (A) Kaplan-Meier comparative survival analysis of recipient mice. Cumulative survival was plotted against days after transplantation. P value was determined by the log-rank test. (B) Quantification of spleen and liver weights in moribund AML mice transplanted with Nras^G12D/+p53^−/− MEPs and age-matched control recipients. (C) Complete blood count analysis of peripheral blood samples collected from moribund AML mice transplanted with Nras^G12D/+p53^−/− MEPs and age-matched control recipients. (D-F) Analysis of donor-derived (CD45.1^–) (D) blast cells (c-Kit⁺), (E) myeloid progenitors, and (F) erythroid differentiation in BM and SP of moribund AML mice transplanted with Nras^G12D/+p53^−/− MEPs and age-matched control recipients. Data are presented as mean ± SD. **P < .01; ***P < .001. Hb, hemoglobin; HCT, hematocrit; PLT, platelet; RBC, red blood cell; WBC, white blood cell.