Cbfβ is expressed in adult hematopoietic stem cells and progenitors.

(A) Cells were isolated from bone marrow of adultCbfb^+/+ (left panel, WT) andCbfb^+/GFP (right panel, GFP) mice and depleted of cells expressing lineage markers (CD3, CD4, CD8, B220, Mac1, GR1, Ter119). Lin⁻ bone marrow cells were stained for c-kit and analyzed by flow cytometry. Representative contour plots (left and right panels) show the distribution of cells with respect to GFP and c-kit PE fluorescence. The c-kit⁺ (c-kit^lo and c-kit^hi) cells from wild-type and heterozygotes were gated and plotted on a histogram to allow comparison of the GFP fluorescence in the 2 populations (middle panel). (B) Bone marrow cells fromCbfb^+/GFP adults were incubated in ACK lysis buffer to eliminate the enucleated erythrocytes and were assessed for GFP expression. The cells were sorted into GFP⁺ and GFP⁻ populations by FACS. Representative contour plots show forward scatter versus GFP profiles of unsorted bone marrow (left panel), and sorted populations (middle and right panels). Progenitors in all 3 populations (unsorted heterozygous bone marrow, GFP⁺, and GFP⁻) were assessed by methylcellulose colony assay. The results are shown in Table 1.