Fig. 4. Representative force histogram and Monte Carlo simulations for L-selectin (A) and E-selectin (B) binding to human PMNs at a reproach velocity of 10 µm second^–1. Simulations were conducted using the Bell model parameters extracted from the non-linear estimation and yielded most frequent and mean rupture forces in accord with those observed experimentally. The area under the force histograms represents the proportion of successful binding events (30% in these cases).