CCND1 and prostate cancer: Another aspect, DPP-4 inhibitors limited the degradation of GLP-1 and glucose-dependent insulinotropic polypeptide to exert effects similar to GLP-1 receptor agonists.[12] Besides, Yang et al found that circular RNA-DPP-4 serves an oncogenic role in prostate cancer progression through regulating miR-195/cyclin D1 axis.[39]