Cellular dynamics of fluorescently labeled proteins can be studied using advanced microscopic techniques like FRAP, SPT, and FRET. In fluorescence recovery after photobleaching or FRAP, a small region containing proteins of interest is irradiated with a focused laser beam to photobleach the fluorophores. As labeled proteins diffuse into the bleached area, the region becomes fluorescent again. The rate of fluorescence recovery determines the diffusion rate of the proteins. Single-particle tracking or SPT involves proteins tagged with fluorophore-bound antibodies. Individual protein movement is tracked using a computer-enhanced video microscope. Forster resonance energy transfer or FRET measures the proximity of two fluorophore-tagged proteins. When the distance is more than ten nanometers, no fluorescence takes place. If the proteins move closer, exciting the donor fluorophore leads to energy transfer to the acceptor fluorophore. The energy transfer reduces the dono's fluorescence while increasing the acceptor's emission, allowing their visualization.