DPP4 and cancer: Moreover, an elevation of its activitywas also found in the peripheral zone of the prostate, where mostprostate cancers arise.26 In humans, higherDPP IV levels in cancerous versus normal prostate tissue were correlatedwith prostate-specific antigen (PSA) level, cancer phase, and bothtumor residue and size.27 In addition,DPP IV activity has been proposed as a marker for thyroid carcinomas28 and can also serve as a first-level diagnosticprocedure to recognize patients with lysosomal storage diseases.29