Transfected CHO cells expressing matched densities of WT or ΔCD human PSGL-1 roll equivalently on P-selectin. (A) Schematic of WT and ΔCD human PSGL-1 constructs. (B) Surface expression of WT and ΔCD PSGL-1 on transfected CHO cells measured by binding of anti–human PSGL-1 mAb PL1. (C) Surface expression of core 2 O-glycans capped with sialyl Lewis x on transfected CHO cells measured by binding of mAb CHO-131. (D) Number of cells rolling on P-selectin at the indicated wall shear stress. (E) Velocities of cells rolling on P-selectin at the indicated wall shear stress. The data represent the mean plus or minus SD from 3 experiments. In panels D and E, rolling was eliminated by anti–human P-selectin mAb G1 or anti–human PSGL-1 mAb PL1.