Autophagy is a process by which cells degrade intracellular components, including organelles, proteins, and foreign bodies. Autophagy is inhibited by mTORC1 and activated by AMPK. The process requires four steps: initiation, formation, membrane expansion, and maturation. These steps are characterized by the structures that are roughly represented by the depicted structures: the omegasome, phagophore, autophagosome and autolysosome. It requires formation of the autophagosome, a double-membrane structure filled with the isolated cytoplasmic material that the cell is removing. The autophagosome eventually fuses with the lysosome to form the autolysosome.