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Figure 2. A) Transfection of siRNA of the ß3 component of the integrin blocks resveratrol (RV) action in MCF-7 cells. Cells were exposed for 48 h to either scrambled RNA (scRNA) or small interfering RNA (siRNA) for integrin 
V or integrin ß3, and treated with or without resveratrol (RV, 10 µM) for the last 4 h. RV-induced ERK1/2 activation and p53 serine-15 phosphorylation were then examined. The representative immunoblots below the graph are of plasma membrane proteins and illustrate the effectiveness of the siRNA transfections for V and ß3. B) [14C]-Resveratrol (RV) binds to MCF-7 cell plasma membranes as well as to integrin monomers V and ß3. Two samples each of purified integrin Vß3 (Chemicon, Temecula, CA, USA) and of plasma membrane proteins from MCF-7 cells were separated by 5% native PAGE. Proteins in one-half of the gel, with one membrane protein and one integrin sample, were transferred to nitrocellulose and subjected to Western blotting with Vß3 Ab ( left panel). Immunoreactive proteins were detected by chemiluminescence. The remaining half of the gel, also containing one membrane protein and one purified integrin sample, was dried and exposed to Imaging Screen K (Bio-Rad, Hercules, CA, USA) and studied by laser densitometry. Identification of monomers in immunoblots was by MW. Additional studies were performed to determine the extent of displaceable binding and are shown in the graph below. Purified integrin Vß3 was incubated with 10 µM [ 14C]-RV in the absence or presence of 1 or 10 µM unlabeled RV for 30 min at room temperature. Samples were separated in 5% native gels, which were dried and analyzed by radioautography. Displacement by unlabeled resveratrol of [ 14C]-RV from the ß3 component of the integrin was then examined. Results shown are representative of three experiments.
