1. Cancer Research UK Receptor Structure Research Group, University of Oxford, Henry Wellcome Building of Genomic Medicine, Division of Structural Biology, Roosevelt Drive, Oxford OX3 7BN, UK.
2. Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
3. Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK.