Comparison of long-term repopulating activity in Thy-1.1^lowSca-1⁺Lin⁻ stem cells separated using Rh-123 (A) or BodVer (B) in the presence of verapamil as an MDR inhibitor. The brightest and dullest 15% of cells in each staining distribution was isolated from Ly-5.1 bone marrow and transplanted into lethally irradiated Ly-5.2 recipient animals in the presence of 10⁵ normal Ly-5.2 bone marrow cells. Each animal (represented by each set of bars in the graphs) was bled 4, 6, 8, and 12 weeks posttransplant (time points are represented by each individual bar in the graphs), and Ly-5.1 peripheral blood cells were identified and phenotyped by flow cytometry.