The Image-iT™ LIVE Mitochondrial and Nuclear Labeling Kit provides two stains - red-fluorescent MitoTracker® Red CMXRos dye and blue-fluorescent Hoechst 33342 dye for highly selective mitochondrial and nuclear staining, respectively in live green-fluorescent protein (GFP)-transfected cells. Using the protocol provided, the dyes can be combined into one staining solution to save labeling time and wash steps while still providing optimal staining.