Levels of GATA-2irGFP- or control vector irGFP-expressing Sca-1⁺ Lin⁻ cells in the bone marrow of animals transplanted with vector-expressing cells. Bone marrow cells were obtained 5 weeks after transplantation from animals transplanted with cells expressing the GATA-2irGFP or control irGFP vector. Staining for the Sca-1 and lineage marker antigens was performed as described in the Materials and Methods. The Sca-1⁺ Lin⁻cell subset in the lower right quadrant was gated on and expression of GFP fluorescence within this cell subset is shown in the histograms below each plot. The percentage of GFP⁺Sca-1⁺ Lin^- cells is indicated above each histogram. Analysis of a representative control irGFP vector animal is shown.