This is always a difficult quesion, and I doubt there is experimental evidence.There is indirect evidence for cellular aborption. We have exposed EA.hy926 cells with trans-resveratrol and showed thta intracellular NO production increased. Appldoorn et al. J.Agric.Food Chem.(2009);57:7693-7699
We have shown that resveratrol is able to bind to specific integrins in breast cancer cells. See our paper published in the Faseb journal in 2006 (attached file).