1. C. N. R. Unit for Muscle Biology and Physiopathology, c/o Department of Biomedical and Experimental Sciences, University of Padova, Via Trieste 75, 35121 Padova, Italy
2. Department of Biology and Molecular Biology Institute, San Diego State University, San Diego, CA 92182, U.S.A.
3. Department of Medicine, Duke University Medical Center, Durham, NC 27710, U.S.A.
4. Department of Physiology and Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0641, U.S.A.