ADP-induced platelet aggregation. Platelets (2 × 10⁸ mL⁻¹ final concentration) were preincubated at 37°C with 250 nmol/L final concentration of the indicated fibrinogen before adding ADP to 10 μmol/L final concentration (indicated by arrows). The increase in light transmission is plotted versus time. Shown are representative curves, with each experiment performed at least four times. (A) Curve 1, normal recombinant fibrinogen; curve 2, recombinant Aα D97E fibrinogen. (B) Curve 1, recombinant Aα DE²/γ 407 fibrinogen; curve 2, recombinant Aα D574E fibrinogen.