1. From the Department of Pathology and Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA; the Department of Internal Medicine (Hematology/Oncology), Pharmacology, and Cancer Biology, Duke University School of Medicine, Durham, NC; the Department of Veterinary Medicine, Tufts University, Boston, MA; the Department of Pathology, Brigham and Women’s Hospital, Boston, MA; and the Department of Biology, Massachusetts Institute of Technology, Cambridge, MA.