Force distribution histograms of fibrinogen binding to Mn²⁺ -activated platelets as measured using laser tweezers. The histograms represent rupture forces greater than 60 pN, previously shown to be specific fibrinogen binding to αIIbβ3.¹⁸  The average yield strength in pN and the cumulative probability of specific fibrinogen binding (%) for each histogram are also shown. (A) Unstimulated platelets. (B) Platelets incubated with 1 mM Mn²⁺ for 5 minutes at 25°C. (C) Platelets incubated with 1 mM Mn²⁺ in the presence of 20 μM tirofiban. (D) Platelets incubated with 1 mM Mn²⁺ in the presence of 100 μg/mL abciximab.