Deletion of Ezh2 induces the differentiation of AML cells and prolongs the survival of diseased mice. (A) Overall survival of mice injected with 4 × 10⁵Ezh2^+/+ or Ezh2^Δ/ΔMLL-AF9–transformed cells compared by Kaplan-Meier analysis (n = 9). **P < .01. (B) Flow cytometric analysis of CD45.2⁺ leukemic cells from BM of recipient mice. The profiles of Gr-1 expression are presented in histograms and the frequencies of the Gr-1^hi fractions and the mean fluorescence intensity (MFI) are also indicated. Representative data from multiple experiments are shown. (C) Pie graphs illustrating the relative frequency of blasts, monocytic cells, granulocytic cells, and granulocytic/monocytic (GM) cells (cells with characteristics of both granulocytes and monocytes) in CD45.2⁺ leukemic cells from BM and PB of moribund mice with advanced leukemia. Cells were cytospun onto glass slides and Wright-Giemsa stained. The frequencies were calculated by counting 500 cells 3 times and the average values are depicted. (D) Representative morphology of leukemic cells from BM in panel C. Magnification ×400 (top panels), ×1000 (bottom panels). (E) Colony assay of leukemic cells from BM of recipient mice with overt leukemia. CD45.2⁺ BM cells (5000 cells each) with indicated genotypes were plated in methylcellulose medium containing 50 ng/mL of SCF, 10 ng/mL of FP6, 10 ng/mL of GM-CSF, and 10 ng/mL of IL-3. The black and gray bars represent compact and dispersed colonies, respectively. The data are shown as the means ± SD for triplicate analyses. **P < .01. Magnification ×100 (top panels), ×200 (bottom panels). (F) Representative colonies in panel E observed under an inverted microscope at the indicated magnifications.