The occurrence and development of gastric cancer usually involve the dysregulation of multiple signaling pathways and cytokines resulting from abnormalities such as TP53 mutations3, RAS and BRAF mutations4, PIK3CA mutations5, methylation-mediated inactivation of hMLH16, and overexpression of HER27, VEGF/VEGFR8 or inflammation-related factors such as COX-29. The gene discussed is PIK3CA; the disease is gastric cancer.