Autophagy, the process of bulk degradation of cellular proteins throμgh an autophagosomic-lysosomal pathway is important for normal growth control and may be defective in tumor cells. It is involved in the preservation of cellular nutrients under starvation conditions as well as the normal turnover of cytosolic components. This process is negatively regulated by TOR (Target of rapamycin) throμgh phosphorylation of autophagy protein APG1. ATG5, another member of the autophagy protein family, forms a conjμgate with ATG12; this conjμgate has a ubiquitin-protein ligase (E3)-like activity for protein lipidation in autophagy. This conjμgate also associates with innate immune response proteins such as RIG-I and VISA (also known as IPS-1), inhibiting type I interferon production and permitting viral replication in host cells.