STOCKHOLM, Sweden -- A University of California, San Diego professor will share the 2008 Nobel Prize in chemistry for discovering a fluorescent protein and developing a method of using it to look inside cells, it was announced Wednesday.

Roger Tsien, a professor of pharmacology, will share the prize with Osamu Shimomura with the Marine Biological Laboratory in Woods Hole, Mass., and Martin Chalfie of Columbia University in New York City.

The scientists were recognized for developing green fluorescent protein, or GFP, which can make cells illuminate, giving researchers the ability to peer into and map their inner workings.

The Royal Swedish Academy of Sciences announced the winners of the Nobel Prize in chemistry today in Stockholm, Sweden.

"This year's Nobel Prize in chemistry rewards the initial discovery of GFP and a series of important developments which have led to its use as a tagging tool in bioscience," according to the Royal Swedish Academy of Sciences.

"By using DNA technology, researchers can now connect GFP to other interesting, but otherwise invisible proteins," according to the academy. "This glowing marker allows them to watch the movements, positions and interaction of the tagged proteins."

The researchers will split a $1.4 million cash prize.

GFP was first observed in 1962 in a species of jellyfish that drifts off the West Coast. It is also found in certain corals.

Since then, it has become one of the most important tools used in bioscience, giving researchers the ability to watch processes that were previously invisible, according to the academy.

Shimomura, an 80-year-old Japanese citizen, who first isolated GFP from the jellyfish, discovered that the protein glowed bright green when exposed to ultraviolet light, according to the academy.

Chalfie, 61, demonstrated the value of GFP as a luminous genetic tag.

Tsien, 56, contributed to the general understanding of how GFP fluoresces and also extended the color palette beyond green allowing researchers to give various proteins and cells different colors.

Tsien described his work as "building molecules to look inside of cells, allowing us to see beyond what the human eye can see."

"Our work is often described as building and training molecular spies, molecules that will enter a cell or organism and report back to us what the conditions are, what's going on with the biochemistry, while the cell is still alive," Tsien said in a statement.

UCSD Chancellor Marye Anne Fox applauded Tsien for earning the Nobel Prize.

"Roger joins the extraordinary and prestigious ranks of Nobel laureates at UC San Diego whose incredible scholarship is dedicated to improving the lives of people throughout the world," she said.