The lysine demethylase LSD1 (KDM1) is required for maintenance of global DNA methylation

En Li and Taiping Chen and colleagues report that lysine specific demethylase 1 (LSD1, also known as AOF2) demethylates and stabilizes DNA methyltransferase 1 (Dnmt1), and that deletion of Aof2 in embryonic stem cells induces progressive loss of DNA methylation.