Abstract: This invention provides a vector comprising an isolated nucleic acid which encodes a protein of interest linked to one or more nucleic acid segments encoding at least two Green Fluorescent Proteins. Provided is the method for detecting a protein of interest in a living cell which comprises: (a) transfecting the living cell with an isolated nucleic acid which encodes the protein of interest linked to at least two Green Fluorescent Proteins. Additional isolated nucleic acids different from the nucleic acid segment of interest may also be linked to at least two nucleic acid which encodes at least two molecules of Green Fluorescent Protein. (b) culturing the transfected cell in conditions permitting expression of Green Fluorescent Protein and the protein of interest; and (c) detecting the fluorescence of the Green Fluorescent Protein, thereby detecting a protein of interest in a cell.