1. Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, U.K.
2. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K.
3. Nuffield Department of Surgical Sciences, University of Oxford, Oxford OX3 7HE, U.K.
4. Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, U.K.
5. Department of Chemistry & Biochemistry, University of California, 607 Charles E. Young Drive East, Los Angeles, California CA90095, United States