EZH2 and systemic lupus erythematosus: Interestingly, a more recent study examining the role of enhancer of zeste homolog 2 (EZH2), which is an enzyme that adds methyl groups to the histone protein H3 at the lysine 27 position, leading to gene repression, showed that EZH2 expression is increased in the peripheral blood mononuclear cells and renal tissues of patients with systemic lupus erythematosus (SLE).