Loss of pleckstrin impairs actin assembly. After stimulation of washed murine platelets with 300 nM PMA, platelets were fixed, permeabilized, and stained with fluorescent phalloidin. Flow cytometry was used to quantitate phalloidin binding in 100 000 cells, and analysis was performed using FlowJo software. Shown is the mean plus or minus SEM for 5 experiments (P < .015).