1. Department of Biochemistry, University of Illinois Urbana-Champaign , Urbana , IL 61801 , USA
2. Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois Urbana-Champaign , Urbana , IL 61802 , USA
3. Cancer Center at Illinois, University of Illinois Urbana-Champaign , Urbana , IL 61801 , USA
4. Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign , Urbana , IL 61801 , USA