To dissect the exact role of DPP4 in autoimmune diseases, future efforts may focus on the role of DPP4 in different types of cells, the temporal and spatial characteristics of DPP4 expression (especially in different stages of disease), unrecognized ligands for DPP4, and strategies targeting the non-enzymatic activity of DPP4. The gene discussed is DPP4; the disease is autoimmune disease.