Activation of PKC-θ by different platelet agonists. (A) Washed and aspirin-treated human platelets were stimulated with 2MeSADP, collagen-related peptide (CRP), and PAR agonists SFLLRN (PAR1) and AYPGKF (PAR4) peptides with various times as indicated at 37°C. (B) Aspirin-treated, washed human platelets were stimulated with SFLLRN (10 μM) and AYPGKF (500 μM) peptides and CRP (10 μg/mL) in the presence or absence of G_q selective inhibitor YM-254890 (50 nm) at 37°C. The stimulation times for all agonists were 60 seconds. The samples were analyzed for threonine phosphorylation of PKC-θ by Western blotting using monoclonal phospho(Thr538)-specific PKC-θ antibody. Equal lane loading was assured by probing the samples with total PKC-θ in the same blot. The Western blot shown is representative of 3 experiments done from 3 different donors. Data were quantified by densitometry and analyzed the fold increase over control. *P < .05.