Author information:
(1)Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, 
the Netherlands; Department of Cell Biology, Erasmus University Medical Center, 
3015 CE Rotterdam, the Netherlands. Electronic address: b.v.steensel@nki.nl.
(2)Department of Cell and Developmental Biology, University of Illinois at 
Urbana-Champaign, Urbana, IL 61801, USA; Carl R. Woese Institute for Genomic 
Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. 
Electronic address: asbel@illinois.edu.