We first examined whether MIEAP, a molecule involved in non–canonical mitophagy, and ATG5, a component of autophagic machinery and involved in canonical mitophagy, are tumor suppressors in thyroid carcinogenesis using genetically engineered mice and found that thyroid cancer development was accelerated in Brafthyr–V600E,Atg5thyr–KO/KO and Brafthyr–V600E,MieapKO/KO mice compared with Brafthyr–V600E mice. This evidence concerns the gene ATG5 and neoplasm.