Platelet COX-2 expression in ET patients and healthy subjects. (A) Flow cytometric histograms of fluorescence intensity on platelets stained for COX-2 in a patient (gray) and a control subject (black). The plot of the patient is shifted to the right, indicating a higher expression of COX-2. (B) Individual values of ΔMFI (see “Platelet immunophenotyping and reticulated platelets” for details) for COX-2 in platelets from patients (n = 41) and controls (n = 22). Horizontal lines indicate medians.