PIK3CA and gastric cancer: The molecular characteristics of EBV-positive gastric cancer were summarized and attributed to mutation of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), overexpression of programmed death-ligand 1 and 2 (PD-L1/2), EBV-CIMP (CpG island methylator phenotype), silencing of cyclin dependent kinase inhibitor 2A (CDKN2A) (p16INK4A), and immune cell signaling (2).