Polycomb group proteins are important for maintaining transcriptional silencing. One conserved PcG complex, PRC2, is composed of several proteins including the histone methyltransferase EZH2, the WD-repeat protein EED (Embryonic ectoderm development), and the Zn-finger protein Suz12. Transcriptional repression mediated by EED involves histone deacetylation, while the EZH2 methylates histone H3 on lysine 27. EED protein is present in four isoforms. These EED isoforms selectively associate with distinct EZH2-containing complexes, resulting in differential targeting of their associated methyltransferase activity. These complexes play a role in Hox gene silencing, X-inactivation, germline development, stem cell pluripotency and cancer metastasis.