Signaling inhibitors affect normal precursor-B cells similar to CD34⁺ cells. CB MNCs were pretreated with pertussis toxin (PTX; 100 ng/mL, 2 hours, 37°C), Toxin B (ToxB; 100 ng/mL, 20 hours, 37°C), or chelerythrine chloride (CC; 10 μM, 30-60 minutes, 37°C) prior to in vitro migration or homing into the BM of NOD/SCID mice. Cells that migrated or homed were gated according to their expression of CD45, and among this population the number of CD10⁺/CD19⁺ precursor-B cells was determined. Results show average (of at least 3 experiments) percentage ± SE of in vitro migration and homing of normal precursor-B CD10⁺/CD19⁺ cells relative to control untreated cells (= 100%). ^*P < .05.