Two scientists who have won acclaim for research into the growth of cancer cells could be candidates for the Nobel Prize in medicine when the 2008 winners are presented on Monday, kicking off six days of Nobel announcements.

Australian-born U.S. citizen Elizabeth Blackburn and American Carol Greider have already won a series of medical honors for their enzyme research and experts say they could be among the front-runners for a Nobel.

Only seven women have won the medicine prize since the first Nobel Prizes were handed out in 1901. The last female winner was U.S. researcher Linda Buck in 2004, who shared the prize with Richard Axel.

Among the pair's possible rivals are Frenchman Pierre Chambon and Americans Ronald Evans and Elwood Jensen, who opened up the field of studying proteins called nuclear hormone receptors.

As usual, the tightlipped award committee is giving no hints about who is in the running before presenting its decision in a news conference at Stockholm's Karolinska institute.

Alfred Nobel, the Swede who invented dynamite, established the prizes in his will in the categories of medicine, physics, chemistry, literature and peace. The economics prize is technically not a Nobel but a 1968 creation of Sweden's central bank.

Nobel left few instructions on how to select winners, but medicine winners are typically awarded for a specific breakthrough rather than a body of research.

Hans Jornvall, secretary of the medicine prize committee, said the 10 million kronor (US$1.3 million) prize encourages groundbreaking research but he did not think winning it was the primary goal for scientists.

"Individual researchers probably don't look at themselves as potential Nobel Prize winners when they're at work," Jornvall told The Associated Press. "They get their kicks from their research and their interest in how life functions."

Blackburn, of the University of California, San Francisco, and Greider, of Johns Hopkins University in Baltimore, won Germany's Paul Ehrlich Ludwig Darmstaedter Prize earlier this year for studying how the enzyme telomerase affects cells.

In 2006, they shared the Lasker prize for basic medical research, often dubbed "America's Nobel," with Jack Szostak of Harvard Medical School. The trio's work set the stage for research suggesting that cancer cells use telomerase to sustain their uncontrolled growth. Continued...