1. The Clarke Institute of Psychiatry (C.W.Y.C., G.M.B.), Toronto, Ontario, M5T 1R8, Canada
2. Medical Research Council Membrane Biology Group (Y.S., M.S.), Department of Medicine, University of Toronto, Medical Science Building, Toronto, Ontario, M5S 1A8, Canada
3. Department of Medicine (M.W.), University of Toronto, Toronto, Ontario, M5S 1A8, Canada
4. Department of Physiology (S.F.P.), University of Hong Kong, Hong Kong