Effect of piceatannol on tyrosine kinase activity. (⧫) Src, (•) Fyn, (□) Syk, or (▴) FAK were incubated with the indicated concentration of piceatannol for 10 minutes at room temperature. The enzymes were then incubated with 0.5 μCi33P γ-ATP for 15 minutes at room temperature. Reactions were stopped by the addition of Laemmli sample buffer and the proteins were separated by SDS-PAGE. Gels were dried down and the radioactive bands were visualized by autoradiography. Densitometry was preformed using a Bio-Rad Imager equipped with Molecular Analyst software. The graph shows the levels of autophosphorylation of relevant enzymes expressed as a percentage of control, where control was the level of autophosphorylation obtained in the absence of piceatannol but with DMSO vehicle present. Similar results were obtained in at least two separate experiments with each enzyme and also when enolase was used as an exogenous substrate.
