Photoactivatable fluorescent proteins are capable of dramatic changes in fluorescent properties in response to specific light irradiation. For example, they can be converted from cyan to green, or from green to red, or from nonfluorescent to a brightly fluorescent state. Several types of such proteins were developed recently, and some of them are already becoming popular tools to study protein mobility. Here we provide detailed recommendations on application of the monomeric green-to-red photoconvertible fluorescent protein Dendra2 for protein tracking in living cultured cells.