DPP9 and renal carcinoma: The first natural substrate of DPP9 identified was the RU134-42 peptide (VPYGSFKHV), and the silencing of DPP9 in the human renal carcinoma cell line BB64-RCC resulted in the increased presentation of the RU134-42 peptide to cytolytic T lymphocytes (CTLs), suggesting that DPP9 may play an important role in antigen presentation (Geiss-Friedlander et al., 2009).