MTOR and neoplasm: Inactivation of phosphatase and tensin homolog (PTEN) gene, a tumor-suppressor gene, occurs in many types of malignancies.17 PTEN protein inactivates the PI3K/AKT/mTOR signaling pathway closely related to the development and drug-resistance of tumors by negatively regulating phosphoinositide-3-kinases.18,19 Loss function of PTEN results in hyperactivation of the signaling pathway.