The Click-iT® EdU Alexa Fluor® 488 Cell Proliferation Assay Kit is a novel alternative to BrdU assays for measuring new DNA synthesis by flow cytometry. EdU (5-ethynyl-2'-deoxyuridine) is a nucleoside analog to thymidine and is incorporated into DNA during active DNA synthesis. Unlike BrdU assays which require harsh treatments to denature the DNA, with the Click-iT® EdU assay, standard aldehyde based fixation and detergent permeabilization is sufficient for the Click-iT® detection reagent to gain access to the DNA. As a consequence the Click-iT® EdU cell proliferation kit is not only easy to use, but compatible with cell cycle dyes and multiplexing for antibody based surface and intracellular markers detection.