About CD26
The DPP4 gene encodes dipeptidyl peptidase 4, which is identical to adenosine deaminase complexing protein-2, and to the T-cell activation antigen CD26. It is an intrinsic type II transmembrane glycoprotein and a serine exopeptidase that cleaves X-proline dipeptides from the N-terminus of polypeptides. Dipeptidyl peptidase 4 is highly involved in glucose and insulin metabolism, as well as in immune regulation. This protein was shown to be a functional receptor for Middle East respiratory syndrome coronavirus (MERS-CoV), and protein modeling suggests that it may play a similar role with SARS-CoV-2, the virus responsible for COVID-19. [provided by RefSeq, Apr 2020]

About Alexa Fluor 405
Alexa Fluor™ 405 (AF405, Alexa 405) has an excitation peak at 401 nm and an emission peak at 421 nm and is similar in size, brightness and application to V450 (BD Biosciences), Vio®Blue® (Miltenyi Biotec), Cascade Blue® (ThermoFisher Scientific), Pacific Blue® (ThermoFisher Scientific). Alexa 405 is most commonly used in flow cytometery, and fluorescence microscopy applications.