[1] Univ Edinburgh, Inst Cell & Mol Biol, Wellcome Trust Ctr Cell Biol, Edinburgh EH9 3JR, Midlothian, Scotland
[2] Mayo Clin, Div Oncol Res, Rochester, MN 55905 USA
[3] Univ Paris 07, Unite Format Rech Biol & Sci Nat, Magistere Genet, F-75005 Paris, France
[4] GlaxoSmithKline, Neurol Ctr Excellence Drug Discovery, Harlow CM19 5AW, Essex, England