 Many methods for introducing DNA sequences into organisms to create recombinant DNA and genetically modified organisms use the process of homologous recombination . Also called gene targeting , the method is especially common in yeast and mouse genetics . The gene targeting method in knockout mice uses mouse embryonic stem cells to deliver artificial genetic material ( mostly of therapeutic interest ) , which represses the target gene of the mouse by the principle of homologous recombination . The mouse thereby acts as a working model to understand the effects of a specific mammalian gene . In recognition of their discovery of how homologous recombination can be used to introduce genetic modifications in mice through embryonic stem cells , Mario Capecchi , Martin Evans and Oliver Smithies were awarded the 2007 Nobel Prize for Physiology or Medicine . 
