Dipeptidyl peptidase 4 (DPP4)

Cell surface glycoprotein receptor involved in the costimulatory signal essential for T-cell receptor (TCR)-mediated T-cell activation. Acts as a positive regulator of T-cell coactivation, by binding at ADA, CAV1, IGF2R, and PTPRC.

Its binding to CAV1 and CARD11 induces T-cell proliferation and NF- kappa-B activation in a T-cell receptor/CD3-dependent method. Its interaction with ADA also regulates lymphocyte-epithelial cell adhesion.