1. Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, Herts, AL7 3AX, United Kingdom
2. Merck Research Laboratories, West Point, PA 19486, United States
3. Dept. of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom