Dysregulation of a gene called REST that is active in nerve cells is thought to play a role in diverse diseases including epilepsy, cancer, Down’s syndrome and Huntington’s disease. Interestingly, we have found that changing REST activity in stem cell lines grown in culture leads to increased survival, not increased death as we suspected. Therefore we have uncovered a new role for REST in regulation of growth and early differentiation decisions in human embryonic stem cells grown in culture.