In living color: seeing cells from outside the body with synthetic bioluminescence
(PHYSorg.com Chemistry)

Glowing creatures like fireflies and jellyfish are interesting to researchers, as their bioluminescent molecules contribute to visualizing a host of biological processes. Now, scientists in Japan have supercharged these molecules, making them hundreds of times brighter in deep tissues and allowing for imaging of cells from outside the body. The bioengineered light source was used to track cancer cells in mice and brain-cell activity in monkeys, but its applications extend beyond the lab.