PIK3CA and osteosarcoma: In recent years, a large amount of evidence has shown that dysregulation of PI3K/AKT pathway is involved in a variety of pathological processes of OS, including OS occurrence, proliferation, metastasis, migration, invasion, cell cycle progression, apoptosis, autophagy, angiogenesis, chemoresistance, Epithelial-Mesenchymal Transition (EMT), aerobic glycolysis, etc. This section introduces the PI3K/AKT pathway and outlines the mechanisms involved in the role of PI3K/AKT pathway in the development of osteosarcoma.