CD274 and cancer: Of interest, whereas we showed upregulation of PD-L1 in several types of cancer cells by ≥IC50 supra-pharmacological dose of grape polyphenol resveratrol and piceatannol, alone and combined [19], a contra-indicated result was obtained in PubMed search demonstrating that in in vitro studies, expression of tumor PD-L1 is suppressed by bio-achievable, pharmacologic dose of flavonoid polyphenols.