PKH and CellVue® Fluorescent Cell Linker Kits provide fluorescent labeling of live cells over an extended period of time, with no apparent toxic effects. Patented cell linker technology incorporates aliphatic reporter molecules into the cell membrane lipid bilayer by selective partitioning. PKH2 and PKH67 are green fluorochromes with excitation (490 nm) and emission (504 nm) similar to fluorescein. PKH26, is a red fluorochrome which, has excitation (551 nm) and emission (567 nm) characteristics compatible with rhodamine or phycoerythrin detection systems. PKH26 may also be excited by the 488 nm emission of an argon-ion laser. CellVue® Claret is a far-red fluorochrome which is independent of pH in physiologic ranges, and has excitation (655 nm) and emission (675 nm) characteristics compatible with a red diode laser. The linkers are physiologically stable and show little to no toxic side-effects on cell systems. Labeled cells retain both biological and proliferative activity, and are ideal for cell tracking and cell-cell interaction studies.