FACS selection of MFG-EGFP-transduced murine BM cells. Dot-plot profiles of mock-transduced (A), MFG-EGFP-transduced total BM cells (B), FACS sorted EGFP-negative (C), and EGFP-positive cells (D) are shown. The number of events obtained in the FL2 emission channel (= red autofluorescence) is plotted versus the number obtained in the FL1 channel (= green fluorescence). Percentages of cells in the sort windows are indicated. Cells from each of these fractions were used for in vitro clonogenic progenitor (GM-CFU) and day 13 CFU-S assays and individual colonies were analyzed for EGFP expression by FACS (Table 1).