Freshly isolated primitive cells from GATA-2^+/– bone marrow have an increased susceptibility for apoptosis. Bone marrow nucleated cells were stained with annexin-V, DNA dye DAPI, Sca-1, c-kit, and lineage antibodies, and Sca1⁺ckit⁺Lin^– cells were analyzed for annexin-V/DAPI activity by flow cytometry. Cells excluding DAPI and binding annexin-V were considered apoptotic (A) (P = .011; n = 6). To examine intracellular Bcl-xL expression, bone marrow nucleated cells were stained with Sca-1, c-kit, and lineage antibodies, and Bcl-xL and the Lin^–c-kit⁺Sca-1⁺ population was analyzed by flow cytometry. Representative flow cytometry plots for Bcl-xL expression are depicted in panel B; the Bcl-xL–positive fraction was defined relative to the isotype control staining (data not shown). M2 represents the % of Bcl-xL–positive cells. Multiple experiments are summarized in panel C (P = .050; n = 5). Error bars depict the standard error of the mean. All statistical analyses were performed using the Student t test.