Moreover, we have had a long-standing interest in the role of CD26 in cancer biology and its suitability as a novel therapeutic target in selected neoplasms [4], particularly in view of its expression in such tumors such as malignant pleural mesothelioma (MPM), renal cell carcinoma (RCC), and T-cell malignancies [5]. Here, DPP4 is linked to renal cell carcinoma.