 H3K4me3 and H3K27me3 marks found on the bivalent domains regulate whether or not an embryonic stem cell differentiates or remains unspecified (pluripotent state).The epigenetic marks contribute to the expression of some genes, and silencing of others during pluripotency and differentiation.H3K27me3 marks repress developmental control genes and stop the cell from differentiating, to ensure that the cell maintains pluripotency.