Stimulation of platelets with TRAP does not cause surface expression or secretion of TFPI. (A) Flow cytometry analysis of platelets stained for TFPI and P-selectin. Quiescent platelets are in the upper left panel. Platelets stimulated with 8 μM TRAP are in the other 3 panels. Dot blot analysis of double-stained cells following activation indicates that 89% of the platelets have surface P-selectin, whereas less than 1% has surface TFPI. (B) Western blot analysis of quiescent and TRAP (8 μM) activated platelets subjected to differential centrifugation. Lane 1, 1500g pellet; lane 2, 10 000g pellet; lane 3, 200 000g pellet; lane 4, 200 000g supernatant.