PIK3CA and neoplasm: Many studies have demonstrated that gain-of-function mutations in the gene encoding the catalytic subunit of PI3Kα, PIK3CA, amplification of PIK3CA, and loss-of-function mutations in PTEN, a lipid phosphatase that dephosphorylates PIP3 result in constitutive activation of the PI3K signaling cascade, which contributes to tumor growth and progression [5], [6], [7].