Background: Proton pump inhibitors (PPI) and potassium-competitive acid blocker (P-CAB) are both effective gastric acid secretion blockers. PPI was reported to inhibit proliferation and induce apoptosis of gastric cancer. However, no study on the effect of Tegoprazan, a novel P-CAB, on gastric cancer have been attempted. Methods: In this study, the anti-cancer effect of tegoprazan in gastric cancer cell line AGS and MKN74 were analyzed with esomeprazole (PPI) as a control. After treatment with tegoprazan and esomeprazole, AGS cells were analyzed with with RNA sequencing and Ingenuity Pathway Analysis (IPA). MTT assays, AnnexinV-FITC/PI staining, flow cytometry and western blot were used for subsequent analysis. The wound-healing assay, matrigel chamber assays, colony forming assay, and western blot of epithelial-mesenchymal transition (EMT) markers were used for analysis of oncogenic and migratory ability. Results: In RNA sequencing and subsequent IPA analysis, tegoprazan significantly increased the pathways involved in cell death of gastric cancer cell compared to esomeprazole. MTT assays proved that tegoprazan inhibits proliferation of AGS and MKN74 cells in dose-dependent manner. AnnexinV-FITC/PI staining and western blot demonstrated that tegoprazan stimulates apoptosis of gastric cancer cells. PI staining and flow cytometry confirmed that tegoprazan blocks G1/S phase entry, finally leading to cell cycle arrest. Moreover, wound-healing assay, matrigel chamber assays, colony forming assay, and western blot of epithelial-mesenchymal transition (EMT) markers indicated that tegoprazan inhibits cell migration, invasion, colony formation, and EMT. To determine key molecule of anti-cancer effect of tegoprazan, upstream regulator analysis in IPA was done and cMYC has strong effect on G1/S phase entry, through PI3K/AKT/GSK3β signaling pathway in this experiment. In this study, the experimental results for tegoprazan showed significant changes compared to esomeprazole. Conclusions: Our findings showed that tegoprazan has more evident anti-cancer effect than esomeprazole. cMYC could be a key molecule for anti-cancer effect through PI3K/AKT/GSK3β signaling pathway by tegoprazan in gastric cancer.