Darrell Irvine is a Howard Hughes Medical Institute Investigator.  Our research is also supported by  the Ragon Institute, the Bill and Melinda Gates Foundation, and the Dept. of Defense (via the Institute for Soldier Nanotechnology and the Defense Advanced Research Projects Agency).  We gratefully acknowledge past support from the the National Science Foundation, the Arnold and Mabel Beckman Foundation, the Whitaker Foundation, DARPA, the Human Frontiers Science Program, 3M, the Dept. of Defense Prostate Cancer Research Program, and the DuPont-MIT Alliance.