Autophagy, the process of bulk degradation of cellular proteins through 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) through phosphorylation of autophagy protein APG1. ATG9A, a multi-spanning membrane protein localizing to the Golgi apparatus and late endosomes, has been proposed to mediate membrane transport to generate autophagosomes. ATG9A has also been implicated as a regulator of STING (stimulator of interferon genes)-mediated innate immune response.