EZH2 and neoplasm: For example, enhancer of zeste homolog 2 (EZH2), the catalytic subunit of the polycomb repressive complex PRC2, has been found overexpressed in several tumors, in which it contributes to H3K27me3-mediated silencing of tumor suppressor genes, besides promoting a self-renewal transcriptional program that allows CSC expansion (249–253).