PTEN inactivation is observed in roughly half of all prostate cancers, where its loss-of-function is associated with poor prognosis, aggressive disease phenotype and castration resistance.44 PTEN functions as a tumor suppressor by inhibiting phosphoinositide 3-kinase (PI3K) activity and subsequent downstream oncogenic signaling through Akt and mTOR. This evidence concerns the gene MTOR and prostate cancer.