(A) MTT assay was performed to evaluate the relative survival rate of FTO gain-of-function cell models treated with three kinds of different antitumor drugs with or without omeprazole preconditioning. **P<0.01 versus cells in indicated groups (Con: cells without any special treatments). (B) Western blot assay was used to estimate the protein expression levels of autophagy-related and apoptosis markers in FTO gain-of-function cell models treated with antitumor drugs. (C) Then cell apoptosis was detected using flow cytometry with annexin V FITC/ PI double staining in FTO gain-of-function cell models treated with three kinds of different antitumor drugs with omeprazole preconditioning. Meanwhile, the relative apoptosis was statistically analyzed, **P<0.01 versus NC cells of corresponding group. (D) FTO enhancement resulted in LC3 puncta further accumulation in AGS and HGC-27 cells treated with antitumor drugs. The representative images of LC3 puncta in GC cells were shown, the magnification was 400× and the number of puncta per cell was counted, **P<0.01 versus NC cells in corresponding groups. (E) MTT assay was performed to evaluate the relative survival rate of FTO gain-of-function cell models treated with 3-MA along with omeprazole preconditioning; **P<0.01 versus Lv-NC cells.