Brief process of autophagy. The process of autophagy includes five steps: initiation, elongation, maturation, fusion and degradation. Firstly, the cargos, which mainly include macromolecules and organelles, are encompassed by a double-membrane vesicle that gradually extends and ultimately forms autophagosome. Then autophagosome fuses with lysosome to form autolysosome, where the cargos are degraded by lysosomal hydrolase and the productions are recycled back to cytoplasm by lysosomal permease. ULK complex, which includes ULK1/2, Atg13, FIP200 and Atg101, is core machinery in initiation stage of autophagy. Beclin1-Vps34-Atg14L-p150 complex is the other key complex, which is required for Autophagosomal nucleation.