PIK3CA and cancer: The phosphoinositide-3 kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway not only plays an important role in cell physiology but is also abnormally activated in a variety of human cancers, leading to cell proliferation, cell apoptosis inhibition, cell cycle acceleration, angiogenesis, and tumor metastasis (Jin et al., 2014).