(A) The total mRNA m⁶A levels in GC cell samples with or without omeprazole treatment were determined by colorimetric method, *P<0.05; **P<0.01,***P<0.001 versus Con (Con: cells without any special treatments). (B) Relative mRNA level of FTO was confirmed by qRT-PCR in GC cell samples with or without omeprazole treatment, **P<0.01 versus cells in corresponding groups (Con: cells without any special treatments). (C) Expression of FTO in GC cells with or without omeprazole treatment were confirmed by Western blot. (D) FTO was up-regulated in GC tissues (TCGA data, Red box for tumor tissue, n=408; gray box for normal tissue, n=211). (E) FTO expression was negatively correlated with disease-free survival in GC patients (TCGA data, high expression, red curve, n=250; low expression, blue curve, n=249). (F) knockdown and overexpression of FTO were validated in both GC cells using Western blot.