Development and use of fluorescent protein markers in living cells.

The ability to visualize, track, and quantify molecules and events in living cells with high spatial and temporal resolution is essential for understanding biological systems. Only recently has it become feasible to carry out these tasks due to the advent of fluorescent protein technology. Here, we trace the development of highly visible and minimally perturbing fluorescent proteins that, together with updated fluorescent imaging techniques, are providing unprecedented insights into the movement of proteins and their interactions with cellular components in living cells.