Internucleosomal DNA fragmentation is a hallmark of apoptosis in mammalian cells. BioVision's Apo-BrdU-Red In Situ DNA Fragmentation Assay Kit provides complete components including positive and negative control cells for conveniently detecting DNA fragmentation by fluorescence microscopy or flow cytometry. The kit utilizes Br-dUTP (bromolated deoxyuridine triphosphate nucleotides) which is more readily incorporated into DNA strand breaks than other larger ligands (e.g., fluorescein, biotin or digoxigenin). The greater incorporation gives rise to brighter signal when the Br-dUTP sites are identified by a Red fluorescence labeled anti-BrdU monoclonal antibody. The assay is suitable for studying apoptosis with GFP transfected cells.