Homing of human mPB CD34⁺ cells in the BM of sublethally irradiated NOD-SCID mice following preincubation with an irrelevant IgG1, the Immu133 (anti-CD34), 12E7 (anti-CD99), or 12G5 (anti-CXCR4) mAbs. Values on the y-axis represent homing of pretreated cells relative to homing of untreated cells. Human cells were detected by flow cytometry using an anti-CD45 mAb. ^*P < .05. Number of experiments (number of animals) is indicated for each group. Error bars represent SEM.