The PI3K pathway controls proliferation, metabolism, survival and motility and is frequently activated in many cancers, often via mutations in PIK3CA, which encodes the α-isoform of the p110 catalytic subunit of PI3K (PI3Kα); loss of PTEN, which antagonizes PI3K function; and overexpression of membrane-bound receptor tyrosine kinase37, 38. The gene discussed is PIK3CA; the disease is cancer.