Enhancer of Zeste Homolog 2 (EZH2) is a methylase of histone H3 that silences gene expression in those regions. It is overexpressed or mutated in gastric, prostate, uterine, breast, and renal cell cancers, as well as in melanoma and most B- and T-cell lymphomas. EZH2 is associated with tumour proliferation and can be used in staining panels to distinguish aggressive lymphomas from less aggressive lymphomas or normal cells.