The Polycomb group - no longer an exclusive club?

Polycomb group (PcG) proteins maintain silencing at target loci in higher e ukaryotes but recent evidence suggests that about half of these proteins ar e also required for maintenance of activation at homeotic loci, We suggest that PcG and trithorax group response elements should acquire a new name, ' maintenance elements', to reflect the dual function of regulatory elements that bind both groups of proteins, New data suggest that there might be a f unctional link between PcG repression and cell-cycle regulation.