Fabien Mongelard and Victor G. Corces are in the Department of Biology, The Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, USA.
Correspondence should be addressed to Victor G. Corces corces@jhu.edu.
Chromatin insulators seem to control eukaryotic gene expression by regulating interactions between enhancers and promoters. Mounting evidence suggests that these sequences play a complex role in the regulation of transcription, perhaps mediated by changes in chromatin structure and nuclear organization.
