MKI67 and mantle cell lymphoma: Compared with EZH2-negative MCL, EZH2+ MCL was associated with aggressive histologic variants (65% vs. 29%, p < 0.001), a high Ki-67 proliferation rate (median, 72% vs. 19%, p < 0.001), and p53 overexpression (43% vs. 2%, p < 0.001) (Figs. 1, 2 and Table 1).