Effect of anti-CD18 and anti–PECAM-1 (CD31) MoAbs on adhesion and transmigration of cytokine-activated mobilized peripheral blood GM-CFCs using HUVECs. Anti–PECAM-1 MoAb was preincubated with endothelium for 20 minutes at 37°C, whereas anti-CD18 MoAb was added to CD34⁺ cells 5 minutes before the start of adhesion or migration assays. All MoAbs were used at 10 μg/mL and were present throughout the assay. Isotype-matched IgG was used as a control in each experiment. Data are the mean ± SEM of four experiments. *P < .05, **P < .01 when compared with control.