An anonymous reader writes "'Gene targeting,' which allows scientists to isolate stem cells in mice and reproduce genetically modified offspring, has won the Nobel Prize for medicine. Having allowed pathologists to better understand diseases such as cancer, heart disease, diabetes and cystic fibrosis for close to 20 years, the technology is just now getting its big day in the sun. From Nobel's full how-it-works: 'Their [i.e. ES cells] use as a vehicle for the transfer into the mouse genome of mutant alleles, either selected in cell culture or inserted into the cells via transformation with specific DNA fragments, has been presented as an attractive proposition. In many of these studies the use of pluripotential cells directly isolated from the embryos under study should have great advantages.'"