MTOR and neoplasm: Several dual PI3K/mTOR inhibitors (e.g., GDC-0980, PF-04691502, BEZ235, XL765, GSK2126458) are currently being developed for clinical use, on the assumption that the vertical blockade of two different crucial nodes along the PI3K signaling pathway might result in more complete pathway inhibition, disruption of pathway-reactivating feedback loops, and eventually enhanced anti-tumor activity [180,181].