The dysregulation of HERV activation restriction genes has also been found in other cancers, such as the overexpression of TET1, TET3, and APOBEC3B but downregulation of APOBEC3C, 3G, 3D, 3H, and C2 in prostate cancer, and different cancers may involve different activation restriction genes [9,10]. This evidence concerns the gene TET1 and cancer.