High correspondence of SLAM cells with the side population is dependent on stringent CD150 gating. (A) Whole bone marrow isotype controls for SLAM family members (CD48, CD41, and CD150). (B) When using SLAM family members to define HSCs, based on isotype controls, 45% of WBM cells are CD150⁺ and 0.4% are CD150⁺CD48⁻CD41⁻ (termed SLAM cells). Only 23% of these cells are c-Kit and Sca-1 positive, and only 20% are side population (SP) cells. (C) When the gating for CD150 is more stringent (asterisks), reducing the number of SLAM cells to 0.01%, then both the percentage of c-Kit⁺ Sca-1⁺ and SP cells within the SLAM population increases to 86% and 84%, respectively. Percentages shown correspond to the gated proportion of the plot.