PTEN regulated collagen-induced platelet activation through PI3K/Akt-dependent and -independent signaling pathways. (A) PP2 (10μM) or the combination of apyrase (Apy; 10 U/mL), indomethacin (Indo) (50μM), and 1B5 (10 μg/mL) inhibited 2 μg/mL collagen-induced aggregation of PTEN^+/+ and PTEN^−/− platelets. PI3K inhibitor LY294002 (25μM) inhibited 2 μg/mL collagen-induced aggregation of PTEN^+/+, but not PTEN^−/− platelets. (B) PP2 (10μM) inhibited 2 μg/mL collagen-induced secretion of PTEN^+/+ and PTEN^−/− platelets. LY294002 (25μM) completely inhibited 2 μg/mL collagen-induced secretion by PTEN^+/+, but not by PTEN^−/− platelets. (C) Akt phosphorylation was inhibited by PP2 (10μM) and LY2940022 (25μM), but not by Apy + Indo + 1B5 in both PTEN^+/+ and PTEN^−/− platelets stimulated with 2 μg/mL collagen. (D) The role of PTEN in regulation of GPVI-mediated signaling pathway.