Asked how he planned to celebrate, Gurdon said he was invited to drinks at 6 o'clock.
"I intend to attend those drinks," he said dryly.
He described his skepticism when first getting the congratulatory call from Stockholm, saying that "the call came from someone in Sweden, and your immediate reaction is: 'Is this right? Is it true or is it someone pulling your leg?'"
Yamanaka told Japanese broadcaster NHK that he was at home doing chores on Monday when he got the call from Stockholm.
"Even though we have received this prize we have not really accomplished what we need to. I feel a deep sense of duty and responsibility," Yamanaka said.
Choosing Yamanaka as a Nobel winner just six years after his discovery is unusual. The Nobel committees typically reward research done more than a decade earlier, to make sure it has stood the test of time.
However, in 2010, the Nobel Prize in physics went to two researchers whose discoveries were also published six years earlier. In 2006, two American scientists won the medicine prize eight years after their work was published.
Prize committee member Juleen Zierath said Gurdon and Yamanaka's discoveries, which also earned them a Lasker award for basic research in 2009, could hold "immense potential," including in developing treatments for Parkinson's disease and in making cells that produce insulin. However, she added that therapeutic implications are still far away.
Experts welcomed the Nobel announcement, praising the duo for their groundbreaking and influential discoveries in a field riddled with ethical debates.
President George W. Bush outlawed federal funding for work on embryonic stem cells that hadn't been derived by a particular date. President Barack Obama overturned that order, allowing access to many more lines of cells.
"Everyone who works on developmental biology and on the understanding of disease mechanisms will applaud these excellent and clear choices for the Nobel Prize," said John Hardy, professor of Neuroscience at University College London. "Countless labs' work builds on the breakthroughs they have pioneered."
The idea of reprograming cells has been put to work in basic research on disease, through an approach sometimes called "disease in a dish."
The reprogramming allows scientists to create particular kinds of tissue they want to study, like lung tissue for studying cystic fibrosis, or brain tissue for Huntington's disease. By reprogramming cells from patients with a particular disease, they can create new tissue with the same genetic background, and study it in the lab. That can give new insights into the roots of the problem.
In addition, that approach allows them to screen drugs in the lab for possible new medicines.
The medicine award was the first Nobel Prize to be announced this year. The physics award will be announced Tuesday, followed by chemistry on Wednesday, literature on Thursday and the Nobel Peace Prize on Friday.
The economics prize, which was not among the original awards, but was established by the Swedish central bank in 1968, will be announced on Oct. 15.
Karl Ritter reported from Stockholm. AP writers Louise Nordstrom in Stockholm, Cassandra Vinograd and Raphael Satter in London, and Elaine Kurtenbach in Tokyo contributed to this report.
Nobel Prize website: http://nobelprize.org
'Blank slate' cells: http://stemcells.nih.gov/info/Regenerative_Medicine/2006chapter10.htm
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