 Bivalent domains have also been found to play a role in developmental regulation in pluripotent embryonic stems cells, as well as gene imprinting.The most common antagonistic epigenetic regulators found together on bivalent chromatin domains are methylation marks on histone 3 lysine 4 (H3K4me3) and histone 3 lysine 27 (H3K27me3).The H3K27me3 mark silences the gene while the H3K4me3 mark allows the gene to not be permanently silenced, and activated when needed.