PREP and neoplasm: In the tumor samples of long-term survivors, for example, SIAE, Prolyl endopeptidase (PREP), Lactotransferrin (LTF), Retinoid-inducible serine carboxypeptidase (SCPEP1) and Dipeptidyl peptidase 4 (DPP4) showed a two-to-threefold increase in the percentage of active form when compared with adjacent-tissue (Fig. 3d).