Green Fluorescent Protein (GFP) is a spontaneously fluorescent protein originally isolated from the jellyfish Aequorea Victoria (Chalfie et al, 1994). GFP has also been recombinant modified and enhanced (called EGFP). GFP and EGFP have been widely used as a valuable reporter molecule for in vivo visualization of gene expression events in a variety of cell types and organisms. Since GFP requires no additional substrates or cofactors, GFP fluorescence can be easily detected under fluorescence microscope. However, most imaging studies of GFP are only qualitative. Since quantitative analysis of GFP expression level in cells or tissues are more informative and have wide applications, BioVision has developed the GFP Quantification Kit which quant