[1] Hammersmith Hosp, Imperial Coll Sch Med, MRC, Clin Sci Ctr,Lymphocyte Dev Grp, London W12 0NN, England
[2] Hammersmith Hosp, Imperial Coll Sch Med, MRC, Clin Sci Ctr,Gene Regulat & Chromatin Grp, London W12 0NN, England
[3] Univ Edinburgh, Inst Cell Anim & Populat Biol, Ashworth Labs, Edinburgh EH9 3JT, Midlothian, Scotland
[4] Fox Chase Canc Ctr, Inst Canc Res, Philadelphia, PA 19111 USA