1. Departments of Physiology and Biophysics (G.S.F., I.S., R.A.S.), University of Washington, Seattle, Washington 98195-7290;
2. Amgen, Inc. (J.W.B.), Thousand Oaks, California 91320
3. Obstetrics and Gynecology (D.K.C., R.A.S.), University of Washington, Seattle, Washington 98195-7290;
4. Zoology (R.A.S.), University of Washington, Seattle, Washington 98195-7290;