Division of Comparative Pathology and Medicine, Department of Pathology, University of California, San Diego, CA 92103, USA. afpoon@ucsd.edu|Division of Comparative Pathology and Medicine, Department of Pathology, University of California, San Diego, CA 92103, USA. afpoon@ucsd.edu|Division of Comparative Pathology and Medicine, Department of Pathology, University of California, San Diego, CA 92103, USA. afpoon@ucsd.edu|Division of Comparative Pathology and Medicine, Department of Pathology, University of California, San Diego, CA 92103, USA. afpoon@ucsd.edu