PECAM-1–deficient platelets demonstrate enhanced secretion on CRP but not thrombin stimulation.

Control PECAM-1^+/+ (white bars) and PECAM-1–deficient (black bars) murine platelets were loaded with 5-HT and stimulated with CRP (5 μg/mL) or thrombin (1 U/mL) for 2 minutes. Platelets were pelleted by centrifugation at 13 000 rpm for 5 minutes, and 5-HT secretion into the medium was determined by scintillation spectrometry. Results are expressed as a percentage of the total tissue content after subtraction of release under basal conditions and are representative of 3 experiments.