Thrombin-induced reversible phosphorylation of MYPT, irreversible phosphorylation of LIMK-1, but reversible dephosphorylation of cofilin during platelet aggregation and secretion: LIMK-1 phosphorylation and changes of cofilin phosphorylation are independent of integrin α_IIbβ₃engagement. Platelet suspensions were not treated (stirring [▪] and nonstirring [▵] conditions) or treated with RGDS (0.5 mM; □) for 2 minutes before stimulation with thrombin (0.5 U/mL). (A) Thrombin-induced MYPT phosphorylation. Platelet lysates were immunoblotted with anti–phospho-Thr696-MYPT antibody. (Left) Graphic representation of results. (Right) Representative immunoblot of MYPT phosphorylation. (B) Thrombin-induced LIMK-1 phosphorylation. Platelet lysates were immunoblotted with anti–phospho-LIMK-1/LIMK-2 (Thr508/505) antibody. (Left) Graphic representation. (Right) Representative immunoblots. (C) Cofilin dephosphorylation and rephosphorylation during thrombin-induced secretion/aggregation. Platelet lysates were immunoblotted with anti–phospho-cofilin antibody. (Left) Graphic representation of results. (Right) Representative immunoblots for cofilin phosphorylation. Values are mean + SD or mean – SD of 3 independent experiments.