Scientific Advisor: David B. Bylund, University of Nebraska Medical Center, Omaha, Nebraska, USA. Scientific Reviewers: Solomon H. Snyder, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; and Frederick Petty, Creighton University School of Medicine, Omaha, Nebraska, USA. Breakthroughs in Bioscience Committee: David L. Brautigan, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Tony T. Hugli, Torrey Pines Institute for Molecular Studies, San Diego, California, USA; Richard G. Lynch, University of Iowa College of Medicine, Iowa City, Iowa, USA; Mary Lou King, University of Miami School of Medicine, Miami, Florida, USA; and Loraine Oman-Ganes, American Society of Human Genetics, Toronto, Ontario, Canada. Breakthroughs in Bioscience Production Staff: Science Policy Committee Chair, John A. Smith, University of Alabama at Birmingham; Managing Editor, Carrie D. Wolinetz, FASEB Office of Public Affairs; and Suzanne Price, FASEB Office of Public Affairs. Thanks to Margaret Crane, who greatly contributed to the early stages of this project.