This is relatively new. But I think it is necessary to put it here before all the historical information. You have to keep this dynamic thing in mind whenever you think about heterochromatin. --I am sure this will be huge in the future.
Proliferation-dependent and cell cycle–regulated transcription of mouse pericentric heterochromatin
Cell cycle regulated transcription of heterochromatin in mammals vs. fission yeast: Functional conservation or coincidence?