In radiation-induced medullary carcinoma in 7M rats, the expression of Ctss and Cxcr4 increased, whereas the expression of seven autophagy regulatory genes (Dapk1, Eif2ak3, Eif4g1, Hgs, Htt, Mapt, and Nfkb1) and one autophagy machinery component (Atg4b) decreased, which was consistent with the decreased gene expression profile in the cancerous region of spontaneous medullary carcinoma in 7M rats. This evidence concerns the gene ATG4B and medullary thyroid gland carcinoma.