Embryonic stem (ES) cells are derived from the inner cell mass (ICM) of the pre-implantation embryo and maintain unlimited self-renewal capacity and multi-lineage differentiation potential. A suite of transcription factors and chromatin regulators are critical for achieving the chromatin landscape in ES cells which remains poised for differentiation without losing pluripotency. An ES cell-specific assembly of BAF, called esBAF, is characterized by the presence of BRG1, BAF250a, BAF60a/b and BAF155, while excluding BRM, BAF250b, BAF60c and BAF170 at the variable positions (Ho et al., 2009b; Kaeser et al., 2008; Kidder et al., 2009) (Figure 1).
