1. Departments of *Surgery,
2. Cell and Developmental Biology, and
3. Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-2733;
4. Nashville Veterans Affairs Medical Center, Nashville, TN 37212-2637;
5. Institute of Biotechnology, University of Helsinki, FIN-00014 Helsinki, Finland; and
6. Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198