Abstract
In recent years, the development of new technologies based on the green fluorescent protein and fluorescence resonance energy transfer has introduced a new perspective in the study of cell biology. Real-time imaging of fluorescent biosensors has made it possible to directly visualize individual molecular events as they happen in intact, live cells, providing important and original insights for our understanding of biologically relevant problems. This review discusses some essential methodological aspects concerning the generation and use of fluorescence resonance energy transfer-based biosensors and presents selected examples of specific applications that highlight the power of this technology.