1. Department
of Biochemistry, University of Cambridge, Cambridge CB2 1QW, U.K.
2. School
of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland
3. Department
of Pharmacology, University of Cambridge, Cambridge CB2 1PD, U.K.
4. Department
of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
5. Department
of Internal Medicine VIII, University Hospital Tübingen, 72076 Tübingen, Germany