1. Department of ChemistryUniversity of Cambridge Lensfield Road Cambridge CB2 1EW UK
2. Present address: MRC WIMM Centre for Computational BiologyMRC Weatherall Institute of Molecular MedicineRadcliffe Department of MedicineUniversity of Oxford Headington Oxford OX3 9DS UK
3. Present address: RIKENCenter for Advanced Intelligence Project Tokyo 103-0027 Japan
4. Cancer Research (UK), Cambridge InstituteLi Ka Shing CentreUniversity of Cambridge Robinson Way Cambridge CB2 0RE UK
5. School of Clinical MedicineUniversity of Cambridge Cambridge CB2 0SP UK