To understand why a cell divides, secretes hormones or transmits a signal to another cell, biologists often use a trick. They attach colored lights to the proteins of interest, so that they can follow the movements and interactions of those proteins in living cells under the microscope. The more colors of these lights are available, the more processes they can follow at the same time.
Click here for original story, Biologists develop new record bright red fluorescent protein
Source: Phys.org