Can controversies be put to REST?

The contribution of REST to embryonic stem (ES) cell pluripotency has been uncertain. Two years ago, Singh et al. claimed that Rest(+/-) and REST knock-down ES cells expressed reduced levels of pluripotency markers, in contrast to a prior and subsequent reports. To understand the basis of this difference, we analysed the YHC334 (YHC) and RRC160 (RRC) gene-trap ES cell lines used by Singh et al., obtained directly from BayGenomics. Both REST mutant lines generated REST-betaGeo fusion proteins, but expressed pluripotency genes at levels similar to appropriately matched parental wild ES cells, consistent with expression being REST-independent.