Kinetics of BM engraftment of MLL-AF9⁺AML cells and its impact on BM stromal cells after transplantation. (A) Representative FACS profile showing the engraftment of normal BM KIT⁺ hematopoietic progenitors and MLL-AF9⁺ AML cells at different time points posttransplantation. (B) Engraftment kinetics of normal BM KIT⁺ hematopoietic progenitors and MLL-AF9⁺ AML cells posttransplantation. Data represent mean ± standard error of the mean from 3 to 4 mice per group per time point. (C) Correlation between BM stromal cell frequencies and AML cell engraftment posttransplantation of MLL-AF9 AML cells. (D) Kinetics of BM cellular niche alterations during development of AML. MLL-AF9 AML cells and BM stromal cell subsets were analyzed in parallel at days 7, 14, 21, and 30 after transplantation of AML cells. Statistical analysis was performed by 2-way analysis of variance analysis with multiple comparisons. *P < .05, **P < .01, and ***P < .001 compared with the control mice. #P < .05 and ##P < .01 to determine the time-related difference in stromal cell frequency. Data represent mean ± standard error of the mean from 3 to 5 mice per group per time point from 3 independent experiments.