Normal PS exposure in platelets lacking the GPIbα N-terminal domain. Washed platelets from WT mice (A) or washed human platelets (B) were treated as in Figure 3 and assayed for annexin V binding by flow cytometry after stimulation with thrombin (10nM) or CRP (10 μg/mL). Results are expressed as the mean percentage (± SEM) of annexin V-positive platelets and are from 3 to 5 independent experiments.