January 2005 – present: Head, Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg July 1998 – present: Professor, Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg July 1994 – June 1998: Associate Professor, Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg October 1989 – June 1994: Assistant Professor, Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg Mat 1985 – September 1989: Postdoctoral Research Associate, Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle