The histone chaperone CAF-1 is known for its role in DNA replication-coupled histone deposition.However,complete removal of its functions causes lethality only in higher multicellular organisms such mice and flies,but not in unicellular organisms such as yeasts.This raises the possibility that CAF-1 may have more important functions than histone deposition during animal development.Evidence is emerging to show that CAF-1 also has a role in the process of higher order chromatin organization and heterochromatin-mediated gene expression;it remains unclear whether CAF-1 has a role in specific signaling cascades to promote gene expression during development.