[The Nobel Prize in Physiology or Medicine 2007 for the development of 'knockout' technology].

The Nobel Prize in Physiology or Medicine 2007 has been awarded to Mario R. Capecchi (University ofUtah, Salt Lake City, USA), O. Smithies (University of North Carolina, Chapel Hill, USA), and Sir Martin J. Evans (Cardiff University, Cardiff, UK) 'for their discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells'. Transgenic mice are often used to study the function of a single gene. The Nobel Prize winners succeeded in silencing the targeted gene in an embryonic stem cell. They went on to introduce it into a blastocyst and then implanted it in a surrogate mother mouse. The blastocyst grew into a genetically modified mouse, better known as a 'knockout' mouse.