Measurement of the strength of ULVWF–P-selectin bond by the optical tweezers. (A) Histogram of forces for ULVWF–P-selectin bond detachment. The detachment forces were arranged into bins and aggregate around integer multiples of the lowest cluster average, 7.2 pN. The average force values for the remaining bins were 14.1 and 22.2 pN, designated by the dashed lines for 2 and 3 bonds, respectively. (B) Plot shows the cumulative results of detachment of ULVWF-coated beads from CHO-P cells. The data in the panel represent the mean values of 40 bead-cell detachments. Error bars represent SEM.