ΔCD neutrophils rolling on P-selectin do not activate β2 integrins to slow rolling on ICAM-1. (A) Velocities of WT neutrophils rolling on P-selectin (45 sites/μm²) without or with coimmobilized ICAM-1 (240 sites/μm²) in the presence or absence of blocking mAb to the indicated protein. (B) Velocities of WT neutrophils rolling on P-selectin (45 sites/μm²) without or with coimmobilized ICAM-1 (240 sites/μm²) in the presence or absence of the Syk inhibitor piceatannol or the solvent control DMSO. (C) Velocities of WT, WT-tr, or ΔCD neutrophils rolling on the indicated density of P-selectin without or with coimmobilized ICAM-1 (240 sites/μm²) in the presence or absence of blocking mAb to ICAM-1. The wall shear stress in all experiments was 1 dyne/cm². The data represent the mean plus or minus SEM from 3 experiments.