Expression of Runx1 in hematopoietic lineages. The filled and open curves indicate GFP expression in wild-type and Runx1-IRES-GFP^k/k cells, respectively. (A) Analysis of GFP expression in cell populations enriched for HSC activity. Bone marrow cells prepared from Runx1-IRES-GFP^k/k and wild-type mice were stained for c-kit using an APC-conjugated antibody and an array of lineage-associated markers using a cocktail of biotinylated antibodies (CD4, CD8, B220, GR-1, Mac1, and Ter119), with the latter revealed by SA-PE staining. The gating strategy is depicted in the dot plot, and panels i and ii show the expression of Runx1-GFP in c-kit^-lin^- and c-kit⁺lin^- cells, respectively. The MFI of the indicated population is shown in the panel. (B) Bone marrow cells were prepared from Runx1-IRES-GFP^k/k and wild-type mice, stained for Ter-119 and c-kit, and GFP expression in c-kit⁺Ter-119⁺ and c-kit^-Ter-119⁺ fractions was determined by flow cytometry. (C) MEL cells were treated for the indicated time with 1.6% DMSO to induce erythroid differentiation. Expression of Runx1 was determined by Western blot analysis using a Runx1-specific antibody; expression of Herf1, an erythroid-specific protein, was also determined to confirm erythroid differentiation.