PIK3CA and gastric cancer: In gastric cancer development, multiple major signaling pathways, including EGFR/HER2, p53, PI3K/AKT, MAPK, TGF-β, Wnt/β-catenin, Notch, JAK/STAT, NF-κB, and Hedgehog, have been identified as essential for regulating apoptosis, cell cycle, proliferation, migration, and invasion [51].