EZH2 and cancer: EZH2 is a member of the polycomb group, whose constituents form two major core protein complexes, PRC1 and PRC2 48, that play important roles in differentiation, maintenance of cell identity, and proliferation 19, 23, 49-51 and are deregulated in a wide variety of cancers, in which they exert oncogenic or tumor-suppressive activity.