PIK3CA and cancer: Some of the major signaling pathways whose components are likely to be cancer drivers include proteins like growth factor receptor tyrosine kinases (e.g., EGFR), lipid kinases (e.g., PI3K), small GTPases (e.g., RAS), oncogenes and tumor suppressors (e.g., MYC, P53), serine/threonine kinases (e.g., RAF, AKT), and cytoplasmic tyrosine kinases (e.g., SRC, ABL) (19–24).