opsin

(via WashU/copyright PNAS)

Researchers at Washington University have genetically-engineered cells to react to light.

By taking light-sensing receptors from the eye — called opsins — and inserting them into immune cells, the researchers were able to trick the cells into moving toward a laser beam, in the same way they would move toward a bacterial infection.

Washington University molecular biologist N. Gautam led the research.