Actin assembly in mouse and human platelets activated by CRP.

(A) F-actin content of CRP- and thrombin-activated mouse platelets. Platelets from WT, SLP-76–deficient mice, and gelsolin-deficient mice activated with 3 μg/mL CRP or 1 U/mL thrombin were fixed with 3.4% formaldehyde, permeabilized with 0.1% Triton X-100 containing 2 μmol/L FITC-phalloidin, and analyzed by FACS. (B) F-actin content of CRP- and thrombin-activated human platelets preincubated with or without 50 nmol/L wortmannin or 25 μmol/L LY294002 for 15 minutes. Results are expressed as the ratio between the fluorescence of activated versus resting cells. Results shown are representative of 3 experiments.