Shear-dependent cell tethering and rolling. The velocity of cells that tethered and rolled on the vWF surface was determined at a wall shear stress of 2 dyn/cm². Over a 5-minute flow period, LβIXV cells tethered to the vWF surface and rolled maintaining continuous surface contact. In contrast, LβIX cells did not tether and roll on the vWF surface. Values are the mean ± SEM, n = 3 to 4.