Sorting and reanalysis of stem cells from 5-FU–treated bone marrow. Bone marrow was harvested from mice that had been treated 3 days previously with 5-FU. RBCs were lysed and the cells were stained with anti-B220, Sca-1, Mac-1, and c-kit. (A) Expression of Sca-1 and c-kit on B220⁻ bone marrow cells. (B) Mac-1 and c-kit expression on B220⁻, Sca-1⁺ gated population as determined in (A). 0.03% of day 3 post 5-FU WBM is contained in the lineage⁻, Sca-1⁺, Mac-1^low, c-kit^low population as shown in the box. The boxed population was sorted and a reanalysis of the expression of B220, Sca-1, Mac-1, and c-kit (C-F, shaded histograms) was compared with the expression of these same molecules on ungated day 3 post 5-FU WBM (C, open histogram) or on B220⁻ day 3 bone marrow cells (D-F, open histograms).