Dr. Capecchi is best known for his pioneering work on the development of gene targeting in mouse embryo-derived stem (ES) cells. This technology allows scientists to create mice with mutations in any desired gene. The power of this technology is that the investigator chooses both which gene to mutate and how to mutate it. The investigator has virtually complete freedom on how to manipulate the DNA sequences in the genome of living mice. This allows scientists to evaluate in detail the function of any gene during the development or post-developmental phase of the mouse. His research interests include the molecular genetic analysis of early mouse development, neural development in mammals, production of murine models of human genetic diseases, gene therapy, homologous recombination and programmed genomic rearrangements in the mouse.