Figure 4.

Inhibition of U46619-induced phosphorylation of ERK 1/2 by flavonoids. Washed platelets, containing ethylene glycol tetraacetic acid (1 mm), were incubated with vehicle [dimethylsulphoxide (DMSO)], flavonoids (100 µm), SQ29548 (10 µm) or the MEK inhibitor U0126 (10 µm), before activation with 5 µm U46619. Platelet lysates were subjected to sodium dodecyl sulphate–polyacrylamide gel electrophoresis and Western blotting with a specific phospho-p44/42 ERK monoclonal antibody. Equal protein loading was verified using antibody against βI tubulin. The upper plot is a representative example from six separate experiments with distinct platelet samples. The lower panel compares the densitometric quantification, using Quantity One software, of U46619-promoted ERK phosphorylation achieved in presence or absence of flavonoids, or U0126 (mean ± SD, n = 6). API, Apigenin; GEN, genistein; LUT, luteolin; QUE, quercetin; RUT, rutin; SQ, SQ29548. *P < 0.05 compared with ERK phosphorylation detected in stimulated platelets in the absence of inhibitors (+DMSO)