1. Department of Molecular Physiology and Biophysics (K.E.S., K.A.B., J.K.O., O.P.M., R.M.O.), Vanderbilt University Medical School, Nashville, Tennessee 37232;
2. Department of Cell Biology and Physiology (A.U., D.W.P.), Washington University School of Medicine, St. Louis, Missouri 63110;
3. Lexicon Pharmaceuticals Incorporated (K.A.P., M.K.S., D.R.P.), The Woodlands, Texas 77381