In fact, a cross-talk between the lymphoid lineage and malignant tumors in vivo have been long discussed and some data about the immune defective antitumor response in many cancers, such as colonic, have been described before, including a defect in IL-12 production [19], which is a well-known CD26 up-regulator on T cells [20]. This evidence concerns the gene DPP4 and cancer.