Acknowledgements
We express our gratitude to Prof. Wouter Lamers and Dr. Jill Hikspoors, from the Univerity of Maastricht in the Netherlands, who produced the reconstruction from which we created the illustration in Figure 1B. We are equally indebted to Dr. Timothy J. Mohun, from the Crick Institute in London, who created the episcopic datasets from which we produced the figures shown in Figures 1A, 2 and 3. It was also Dr Mohun who produced the abnormal mice with perturbation of the Furin enzyme.