Highly enriched p190-B^−/− HSCs exhibit enhanced long-term engraftment. Competitive repopulation assay of purified LSK FL cells. LSK FL cells (1500) plus 1.0 × 10⁶ FL competitor cells were injected into lethally irradiated recipients. (A) Percentage of CD45.2⁺ cells (left panel) and absolute number of CD45.2⁺ cells (right panel) in the PB at the indicated time points after transplantation (mean ± SD; n = 4). (B-C) Histograms show the percentage of CD45.2⁺ in the PB (B) and BM (C) 4 to 6 months after primary and secondary transplantation (mean ± SD; n = 6). (D) Flow cytometry analysis dot plot of LSKCD150⁺CD48⁻ frequency in CD45.2⁺ BM cells from secondary recipient. (E) Frequency of LSKCD150⁺CD48⁻, LSK, and LK cells in CD45.2⁺ BM cells of primary and secondary recipients 4 to 6 months after transplantation. Data are mean ± SD; n = 6.