The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) and PI3K/AKT/mTOR are two parallel signaling pathways controlling proliferation, survival, metabolism, and invasion of cancer cells that are commonly activated by RTKs, whereas Src, STAT, and phospholipase C-γ pathways are additional pathways activated by most RTKs. Here, PIK3CA is linked to cancer.