3Dye Minimal Labeling Kit for two-dimensional difference gel electrophoresis. This 3Dye Kit is a specially designed set of fluorophores for the efficient assay of complex mixtures of proteins (proteomes). The Kit allows precise comparison of protein expression in two or three samples of lysates. Perfect mobility matching and bright dye fluorescence allows for high efficiency detection and high resolution of minor proteins on 2D gel electrophoresis. Each kit contains three dyes: two for both samples, one for the internal standard. Auxiliary components are included as well. The Kit is compatible with all imagers capable of detection of Cy2, Cy3, and Cy5 dyes. The gels labeled with Lumiprobe 3Dye 2D DIGE Kit are ready for subsequent mass-spectrometrical analysis. Each 3Dye 2D DIGE Kit contains reactive NHS esters of Cyanine2, Cyanine 3, and Cyanine 5 dyes, and labeling grade dimethylformamide (DMF) solvent. Cyanine2 can be used as a reference which can be added to both samples. Reactive dyes are supplied in a lyophilized form, which prolonges the shelf-life of the Kit. Each tube contains exactly the same quantity of reactive dyes (variation within 10%). Re-constitution of the NHS esters with included DMF guarantees that labeling efficiency of Cyanine2, Cyanine 3, and Cyanine 5 remains the same during entire term of kit use.