Used in research and diagnostic applications to detect and quantify DPP4 (dipeptidyl peptidase-4) or CD26 expression on cell surfaces. Plays a role in immunological studies involving T-cell activation and regulation, as CD26 is a co-stimulatory molecule involved in immune responses. Employed in flow cytometry, immunohistochemistry, and Western blotting to study DPP4/CD26 distribution in tissues and cell lines. Also utilized as a reference standard in the development of therapeutic antibodies targeting DPP4 for conditions such as type 2 diabetes and certain cancers. Supports drug discovery and biomarker validation by enabling precise targeting and inhibition studies of DPP4 enzymatic activity.