Among these ATG genes, one subgroup, consisting of approximately 18 genes (Table 2), is shared among the various types of autophagy including nonselective macroautophagy, the cytoplasm to vacuole targeting (Cvt) pathway (a biosynthetic autophagy like pathway), mitophagy and pexophagy. More specifically, the corresponding gene products of this subgroup are required for autophagosome formation, and thus are termed the core autophagy machinery.