Deletion of Ezh2 attenuates the progression of leukemia and causes a reduction in the frequency of LICs. (A) Summary of secondary transplantation of primary leukemic cells. Limiting numbers of Ezh2^+/+ or Ezh2^Δ/Δ CD45.2⁺ leukemic cells isolated from BM of primary recipients were transplanted immediately into sublethally irradiated secondary recipient mice (CD45.1⁺). Mice with chimerism of more than 1% in the PB at 20 weeks after transplantation were considered to be engrafted successfully, and the others were defined as negative mice. The frequencies of positive mice and LICs and the 95% confidence interval (95% CI) are indicated in the table. (B) Overall survival of mice injected with Ezh2^+/+ or Ezh2^Δ/Δ leukemic cells (10, 500, or 10 000 cells; n = 5 each, *P = .0017). (C) Percent chimerism of donor cells in PB. The chimerism of CD45.2⁺ donor-derived cells in PB of recipients infused with 10 000 leukemic cells was examined after transplantation. Three mice with Ezh2^Δ/Δ leukemic cells did not show engraftment of donor cells (n = 5 each). (D) Pie graphs illustrating the relative frequency of blasts, monocytic cells, granulocytic cells, and granulocytic/monocytic (GM) cells in CD45.2⁺ leukemic cells from BM 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.