GFP, originally derived from the jellyfish Aequorea victoria, has become one of the most popular reporter genes due to its inherent fluorescence, which does not require additional substrates or cofactors. Its non-toxic nature and ease of visualization under a fluorescence microscope make it highly suitable for live-cell imaging. Moreover, various GFP variants with different spectral properties have been developed, facilitating multi-color labeling in complex tissues.
