ATG5 and neoplasm: Heterozygous disruption of BECN1 leads to spontaneous tumor formation in mice, indicating BECN1 is a halpoinsufficient tumor suppressor,10, 11, 12 mice lacking ATG5, ATG7 or AMBRA1 show similar effect.13, 14, 15 However, autophagy is also involved in oncogenic process in some circumstances.