EZH2 (enhancer of zeste homologue 2), also known as Enx1, is a member of the polycomb group of proteins and is involved in cell cycle regulation. EZH2 represses transcription via trimethylation of histone H3 on Lys27 (H3K27) as indicated by the fact that RNAi-mediated knockdown of EZH2 resulted in a loss of H3K27 trimethylation. EZH2 is ubiquitously expressed during early embryo genesis, and becomes restricted to the central and peripheral nervous systems and sites of fetal hematopoiesis during later development. In the adult, EZH2 is restricted to the spleen, testis and placenta. EZH2 and BMI-1 genes are coexpressed in Reed-Sternberg cells of Hodgkin