p190-B^−/− HSC/P exhibit normal cell-cycle rate and survival during serial transplantation. (A) Cell-cycle status of WT and p190-B^−/− LSKCD150⁺CD48⁻ cells. BM LSKCD150⁺CD48⁻ cells of primary and secondary recipients were stained with Hoechst 33342 dye and Pyronin Y. Histograms represent the percentage of CD45.2⁺ LSKCD150⁺CD48⁻ cells and LSK cells in G₀, G₁, and S/G₂M phases of the cell cycle (mean ± SD; n = 5). (B) Apoptosis analysis of LSKCD150⁺CD48⁻ cells. BM cells from secondary transplantation recipients were stained with annexin V and analyzed by flow cytometry. Data represent the percentage of CD45.2⁺ LSKCD150⁺CD48⁻ and LSK annexin V⁺ cells (mean ± SD; n = 5). (C) PB recovery after a single dose of 5-FU. Kinetics of neutrophil PB counts are shown (mean ± SEM; n = 3 independent experiments, n = 5 mice per group and experiment). (D) The proliferation of LSCD150⁺CD48⁻ cells was measured by in vivo BrdU incorporation over 15 hours. Histogram is percentage of LSCD150⁺CD48⁻, which incorporated BrdU (mean ± SD; n = 3).