To maintain the undifferentiated state, ES cells need to keep silent differentiation genes. However, the genetic invalidation of key systems of epigenetic repression (Polycomb, H3K9 and CpG methylation) does not impair ES cells self-renewal. This suggests that silencing of developmental genes may be reestablished after each division owing to the highly efficient action of the pluripotency gene regulatory network. Under this context, the existence of a memory of gene activation would be particularly interesting to accelerate the re-establishment of the network upon re-entry into G1. We hypothesize that some pluripotency regulators may act as bookmarking factors by remaining bound to critical target genes during mitosis. This would enable the rapid and efficient re-establishment of the network after mitosis such that self-renewal is efficiently preserved. Using imaging and ChIP-Seq approaches we have identified one such pluripotency transcription factor.