PIK3CA and cancer: This would represent a paradigm shift in our understanding of the action of PI3K in human cancer biology and would perhaps establish novel therapies targeting core PI3K pathway factors, including PI3K and mTOR, for which US Food and Drug Administration (FDA)-approved drugs which can cross the blood brain barrier already exist, including BKM120 and everolimus [74,75], in combination with drugs specifically targeting transcription factors and/or co-factors.