What is DAPI a marker of?

DAPI is used as a marker for applications such as fluorescence microscopy, cell imaging applications, cell viability, membrane viability, and cell cycle analysis in flow cytometry. It is a marker for membrane viability, as it passes more effectively in fixed cells than live cells. DAPI is used in the cell cycle to stage cells since it binds efficiently to dsDNA and saturates the nucleic acids. It is also useful for fluorescence microscopy, as it exhibits a 20 fold enhancement of fluorescence upon binding to A-T rich regions. Cellular imaging allows for the extraction of the nuclear features area and total intensity of DAPI-stained nuclei.