Enhanced green fluorescence protein (eGFP) is a 27 kDa protein derived from the jellyfish Aequorea victoria, which emits green light (emission peak at a wavelenth of 509 nm) when excited by blue light (excitation peak at a wavelenth of 395 nm). eGFP has become an invaluable tool in cell biology research, since its intrinsic fluorescence can be visualized in living cells. eGFP has been widely used as a reporter for gene expression, enabling researchers to visualize and localize eGFP-tagged proteins within living cells without the need for chemical staining. Other applications of eGFP include assessment of protein protein interactions through the yeast two hybrid system and measurement of distance between proteins through fluorescence energy transfer (FRET) protocols.