Analysis of K562 transfectant rolling on E- and P-selectin under defined shear flow. Velocity distributions of the different cell lines on CHO cells transfected with E- or P-selectin. Histograms depict the distribution of velocities from 0 to 50 μm/s at 1.9 dynes/cm2 of linear shear stress. #, total events between 0 and 50 μm/s; v, mean of velocity measurements ± SE.