The 2007 Nobel Prize for Medicine has been won by scientists researching stem-cell changes.
Mario Capecchi, Martin Evans and Oliver Smithies have been awarded the prestigious 10m Swedish crown (€1.09m) prize for their work on introducing genetic changes in mice using embryonic stem-cells.
Dr Capecchi was born in Italy and is Professor of Human Genetics and Biology at the University of Utah.
Sir Martin Evans FRS is Professor of Mammalian Genetics at Cardiff University.
Dr Smithies, who is English by birth, is Professor of Pathology in the University of North Carolina at Chapel Hill.
Medicine is the first of the Nobel prizes to be awarded each year.
The prizes for achievement in science, literature and peace bearing the name of Alfred Nobel were first awarded in 1901 according to the will of the Swedish dynamite millionaire.