Phosphorylation of GSK3βser9 is reduced by an inhibitor of PI3K and by deletion of 3 alleles of Akt in mouse platelets. (A) Washed mouse platelets from WT mice (□) or Akt1^+/− Akt2^−/− mice (■) in the presence or absence of LY294002 (100 μM) were stimulated with mouse TRAP (PAR4 agonist) AYPGKF (1 mM) for 10 minutes, then lysates were immunoblotted with an antibody to phospho-GSK3β-ser9. (B) The fold increase in GSK3β phosphorylation after AYPGKF treatment (± LY294002) was analyzed by densitometry. The means (± SD) are shown. (*P ≤ .05 by unpaired t test, **P ≤ .01by unpaired t test, n = 3.)