For the discovery and development of green fluorescent protein GFP (Green Fluorescent Protein) Osamu Shimoura, Martin Chalfie and Roger Y. Tsien were awarded the Nobel Prize for chemistry.
The GFP protein was observed for the first time in 1955 in Aequorea victoria jellyfish, who lives along the west coast of North America, and was isolated in 1962 by Shimomura, who realized that its properties to shine a green light when strucks by ray ultraviolet.
Since these discovery, more techniques were develpoed for observe phenomena, that otherwise couldn't be osbserved. Chalfie, thanks to an experiment in which it is able to mark cells of the small transparent worm Caenorhabditis elegans, has sensed the potential of the protein whose mode of fluorescence were later clarified by Tsien.
Knowledge of GFP is that now that the protein is available in various colors, making it possible to "follow" evolve in different biological processes inside cells .