Figure 1.
ES cell self-renewal and differentiation. ES cells have the ability to self-renew or differentiate into cells of all three germ layers (endoderm, ectoderm, and mesoderm). In ES cells, OCT4, SOX2, and NANOG form a core transcriptional network influencing the stem cell self-renewal machinery. Several hundred target genes co-occupied by OCT4, SOX2, and NANOG can be classified into two groups of downstream genes exerting opposing functions. One group includes actively transcribed genes associated with proliferation and transcription factors necessary to maintain the ES cell state. The other group includes transcriptionally silent genes encoding developmental regulators that are only activated as cells differentiate and commit to particular lineages.