Purified CSL3 is conjugated to cyanine 3 (Cy3) fluorescent dye. Cyanine dyes are better able to withstand the harsh dehydration and embedding conditions required for mounting sections in non-polar plastic media, and are brighter in a non-polar environment than in an aqueous medium. Advantages of plastic over aqueous mounting media are brightness, contrast, and longevity of the fluorescence. Advantage of Cy3 conjugates are bright and photostable in the aqueous environment as well as in non-polar media. Cy3 has an approximate peak excitation wavelength of 550 nm and an emission wavelength at 570 nm. This product comes in a stabilized liquid form.