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. Author manuscript; available in PMC: 2009 Apr 1.
Published in final edited form as: Curr Opin Genet Dev. 2008 Mar 12;18(2):109–115. doi: 10.1016/j.gde.2008.01.010

Figure 2. Inactive Gene Promoters in ES Cells.

Figure 2

Models of gene regulation in ES cells. (a) H3K4 tri-methylation and an initiating form of RNA polymerase II are evident at promoters of some inactive genes. These genes may be regulated at the level of the transition from initiation to elongation [13]. (b) A significant subset of inactive genes in ES cells, including many lineage-specifying transcription factor genes, are dually marked by tri-methylation at H3K4 (active) and at H3K27 (repressive). The relevant genes are largely silent in ES cells. The presence of the activating mark may keep them poised for activation upon ES cell differentiation [18,31].