The PI3K/AKT/mTOR pathway is an intracellular signaling pathway that plays a pivotal role in the regulation of cell cycle. It is directly related to cellular quiescence, proliferation, cancer, and longevity. Phosphorylation of PI3K activates AKT which regulates several downstream molecules (e.g. mTOR). Several factors may constitutively activate the PI3K/AKT/mTOR signaling pathway, such as EGF, shh, IGF-1, insulin, and CaM. On the other hand, PTEN, GSK3B and HB9 are inhibitors of the pathway. In many cancers, this pathway is overactive, thus reducing apoptosis and allowing proliferation. This pathway is necessary, however, to promote growth and proliferation over differentiation of adult stem cells, neural stem cells specifically. Additionally, this pathway has been found to be a necessary component in neural long term potentiation.