Csf2rb⁻/lin⁻ BM cells in mice expressing Cbfb-MYH11 are enriched for preleukemic progenitors and leukemia-initiating cells. (A) FACS staining of lineage-depleted bone marrow cells from ENU-treated, preleukemic Cbfb^+/56M, Mx1-Cre mice 14 days after induction of Cbfb-MYH11. Cells were sorted for Csf2rb expression as indicated by the boxes, and transplanted into sublethally irradiated mice via retro-orbital injection. (B) Kaplan-Meier survival curves of mice that received a transplant of preleukemic Csf2rb⁻ or Csf2rb⁺ cells. (C) FACS staining for the indicated differentiation markers in the Csf2rb⁻ and Csf2rb⁺ leukemic spleen cells from a representative mouse that developed AML after transplantation of preleukemic Csf2rb⁻ cells. (D) Western blot of CBFβ-SMMHC expression in the Csf2rb⁻ and Csf2rb⁺ leukemic cells of 2 different recipient animals. (E) Kaplan-Meier survival curves of secondary transplant recipient mice that underwent transplantation as described in panel A with leukemic Csf2rb⁻ and Csf2rb⁺ cells.