In vivo Ho uptake by BM HSCs and by multipotent and lineage-restricted progenitor cells according to the SLAM code phenotype. C57BL/6 mice were perfused with Ho dye intravenously 10 and 5 minutes before tissue sampling; BM cells were harvested on ice in the presence of verapamil and reserpine to block ATP-dependent transporters and stained for lineage, CD41, Sca-1, KIT, CD48, and CD150 surface antigens. (A) Representative dot plot of Sca-1 versus KIT expression on viable 7-amino-actinomycin D⁻Lin⁻CD41⁻–gated BM cells. (B) Dot plot of CD48 versus CD150 expression on Lin⁻CD41⁻Sca-1⁺KIT⁺ cells gated in panel A. (C-E) Representative dot plots of Ho blue fluorescence versus Ho red fluorescence of gated viable Lin⁻CD41⁻Sca-1⁻KIT⁺ lineage-restricted progenitors, Lin⁻CD41⁻Sca-1⁺KIT⁺CD150⁻ short-term reconstituting multipotent progenitors, and Lin⁻CD41⁻Sca-1⁺KIT⁺CD48⁻CD150⁺ HSCs, respectively. (F) Distribution of Hoechst bright, medium, and negative cells among Lin⁻CD41⁻Sca-1⁻KIT⁺ (L−S−K+), Lin⁻CD41⁻Sca-1⁺KIT⁺CD150⁻ (LSK150−), and Lin⁻CD41⁻Sca-1⁺KIT⁺CD48⁻CD150⁺ (LSK CD48−CD150+) populations. Data are average ± SD from 8 mice.