1. Department of Physiology and Biophysics, University of California, 19172 Jamboree, Irvine, California 92697, Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California 90033, Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66160-7421, and Musculoskeletal Research Laboratories, Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland 21201