Fluorescent labels have long been useful to biomedical researchers interested in studying the structure and function of proteins and how they interact with their environment. Researchers 'label' proteins by attaching a fluorophore, or fluorescent molecule, to the protein that they are interested in studying. In the past, the most commonly used fluorescent label was Green Fluorescent Protein (GFP), which comes from jellyfish. Labels also find many applications in fluorescence spectroscopy