[1] Univ Basel, CH-4003 Basel, Switzerland
[2] Spanish Natl Canc Res Ctr, HHMI, Madrid, Spain
[3] Max Planck Inst Mol Cell Biol & Genet, Dresden, Germany
[4] Stanford Univ, Stanford, CA 94305 USA
[5] UCSD, La Jolla, CA USA
[6] Univ Sao Paulo, BR-05508 Sao Paulo, Brazil