1. Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey SM2 5NG, U.K.
2. Cancer Research Technology Discovery Laboratories London, Wolfson Institute for Biomedical Research, The Cruciform Building, Gower Street, London WC1E 6BT, U.K.
3. Section of Structural Biology, Chester Beatty Laboratories, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, U.K.