Activating mutations of the H3K27 histone methyltransferase EZH2, a component of the polycomb repressive complex 2, are found in 10 to 25% of FL cases and 20% of GCB-DLBCL cases (14, 18, 19, 53–55, 88–90). Here, EZH2 is linked to diffuse large B-cell lymphoma.