7-aminoactinomycin D (7-AAD) is a fluorescent intercalator that undergoes a spectral shift upon association with DNA. 7-AAD/DNA complexes can be excited by the 488 nm laser and has an emission maxima of 647 nm, making this nucleic acid stain useful for multicolor fluorescence microscopy and flow cytometry. 7-AAD appears to be generally excluded from live cells, but can be used with cells that have been fixed and permeabilized. 7-AAD has been used for cell cycle analysis by flow cytometry. 7-AAD also binds selectively to GC regions of DNA yielding a distinct banding pattern in polytene chromosomes and chromatin for use in chromosome banding studies.