Both apyrase and the PI 3-kinase inhibitor wortmannin specifically affect the association of myosin heavy chain with the cytoskeleton and the organization of signaling complexes. (A) Cytoskeletons were isolated from 40 μmol/L TRAP-treated platelets at various time points in the absence (•) or in the presence of 1 U/mL apyrase (○) or 100 nmol/L wortmannin (□). Cytoskeletal proteins were separated by a 7.5% SDS-PAGE and visualized by Coomassie Blue staining. Actin and the major actin-binding proteins were quantified by densitometric analysis (ScanMaker IIHR, Microtek, Germany). The relocation of p85 (B) and RhoA (C) to the cytoskeleton was analyzed by Western blotting with specific antibodies. Data shown are representative of 3 independent experiments with similar results.