1. Columbia University Medical Center (J.B.), New York, New York 10032
2. University of Texas Medical Branch (K.L.P.), Galveston, Texas 77555
3. University of Texas Health Sciences Center (R.D.S.), Houston, Texas 77030
4. VA Palo Alto Health Care System and Stanford University (A.R.H.), Palo Alto, California 94305
5. Genentech, Inc. (T.M., B.L.), South San Francisco, California 94080