PTGS2 and gastric cancer: A vitamin E analogue γ-tocotrienol, which is already in clinical trials, can reduce the resistance and can potentiate the apoptotic effects of capecitabine against gastric cancer via inhibition of NF-κB and the NF-κB-regulated expression of COX-2, cyclin D1, and MMP-9 in various gastric cancer cell lines and in xenografts from human gastric cancer [182].