The mouse Etl1 gene encodes a nuclear protein belonging to the rapidly growing SNF2/SWI2 family. Members of this family are related to helicases and nucleic-acid-dependent ATPases and have functions in essential cellular processes such as transcriptional regulation, maintenance of chromosome stability and various aspects of DNA repair. The ETL1 protein is expressed from the two-cell stage onwards, throughout embryogenesis in a dynamic pattern with particularly high levels in the thymus, epithelia and the nervous system and in most adult tissues. As a first step to address the role of ETL1 in cells and during development, we inactivated the gene by homologous recombination. ES cells and mice lackin
