1. Department of Cell and Molecular Biology (H.A., E.M., Y.P., M.H.-D.), Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
2. The School of Molecular Biosciences (J.W.), Washington State University, Pullman, Washington 83843
3. Department of Medicine (E.J.L.), Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
4. Division of Medicine (M.A.), University College, London WC1 E6JJ, United Kingdom