Fig. 4. PI 3-kinase involvement on filopodia extension and actin polymerization induced by excess PL. Scanning electron micrographs showing the representative morphology for resting platelets (a); resting platelets incubated with 1% of DLPC for 2 minutes (b); resting platelets pre-treated with 100 nM wortmannin for 15 minutes and then incubated with 1% of DLPC for 2 minutes (c). Bar, 1 µm. (d) Actin filament content in different cell extracts as measured by the Dnase 1 inhibition assay. Ctrl, the actin filament content in resting platelets; WCtrl, the actin filament content in platelets pre-incubated with 100 nM wortmannin for 15 minutes; DLPC, the actin filament content in resting platelets incubated with 1% of DLPC for 2 minutes; WDLPC, the actin filament content in resting platelets pre-incubated with 100 nM wortmannin for 15 minutes; LYDLPC, the actin filament content in resting platelets pre-incubated with 50 µM LY294002 for 15 minutes before addition of PC; PMA, the actin filament content in platelets stimulated with 100 nM PMA for 20 minutes; WPMA, the actin filament content in resting platelets before addition of PMA. (e) The quantification of PtdIns(3,4)P₂ in resting platelets (Ctrl); in platelets incubated with DLPC for 2 minutes (DLPC), in platelets pre-incubated with 100 nM wortmannin (WDLPC) or 50 µM LY294002 (LYDLPC) 15 minutes before addition of DLPC; and in platelets stimulated with 1 Unit/ml of thrombin (Thb). The data are expressed as the mean of four individual experiments ± s.d.