Kehlen et al. reported that undifferentiated anaplastic thyroid carcinomas expressed larger amounts of APN/CD13 than differentiated thyroid carcinomas, whereas in contrast, higher levels of DPPIV/CD26 were expressed in follicular and papillary thyroid carcinomas than in undifferentiated anaplastic thyroid carcinomas [23]. This evidence concerns the gene DPP4 and differentiated thyroid carcinoma.