DPP4 and neoplasm: We found that liver metastasis is significantly associated with serum CEA levels (P<0.001), serum CA19-9 levels (P <0.001), extra nodal tumor deposits (P<0.001), CD133+ subpopulation (P <0.001), CD133+CD44+ subpopulation (P=0.001), CD133+CD54+ subpopulation (P<0.001), CD133+CD44+CD26+ subpopulation (P<0.001) and CD133+CD44+CD54+ subpopulation (P<0.001).