Analysis of hematopoietic progenitor cells in Runx1^R188Q/+ BM. (A-C) Flow cytometry analysis of WT and Runx1^R188Q/+ BM cells for early (Mac1⁺Gr1^low, A) and late (Mac1+Gr1+, B) granulocytic progenitor cells, and monocytic progenitor cells (C). (D) Colony-forming unit (CFU) assay using BM cells from WT and Runx1^R188Q/+ mice. Graph depicts monocyte (M), granulocyte (G), granulocyte/monocyte (GM), granulocyte/monocyte/erythroid/megakaryocytic, and burst forming colony (BFU) -erythroid colonies. (E-F) Flow cytometry analysis for B and T cells in WT and Runx1^R188Q/+ BM cells. (G) Ploidy analysis in megakaryocytes of WT and Runx1^R188Q/+ BM. (H-I) Quantification of nuclei with 53bp1-positive foci in WT and Runx1^R188Q/+ Lin^dep BM cells, 2 hours after 2 Gy ionizing radiation (H), and pretreated for 1 hour with imatinib (I). ∗P < .05, ∗∗P < .005; ns, not significant.