PKC-θ-mediated syntaxin-4 phosphorylation. Washed human platelets were stimulated with CRP (10 μg/mL) and AYPGKF (100 μM) at 37°C in the presence of PKC-θ RACK peptide or control peptide and then immunoprecipitated for syntaxin-4, and immunoblotted for phosphorylation on threonine residues of syntaxin-4. Normal mouse IgG served as a negative control. Phosphorylation data were quantified and analyzed in fold increase over control.