The protein encoded by this gene is identical to adenosine deaminase complexing protein-2, and to the T-cell activation antigen CD26. It is an intrinsic membrane glycoprotein and a serine exopeptidase that cleaves X-proline dipeptides from the N-terminus of polypeptides. DPP4 (Dipeptidyl Peptidase 4) is a Protein Coding gene. Diseases associated with DPP4 include Nasopharyngitis and Mental Depression. Among its related pathways are Collagen chain trimerization and Incretin synthesis, secretion, and inactivation. GO annotations related to this gene include protein homodimerization activity and receptor binding. An important paralog of this gene is FAP.