MKI67 and B-cell non-Hodgkin lymphoma: Interestingly, we also found that EZH2 expression was significantly more frequent amongst proliferating (Ki67+) versus resting (Ki67−) cells, indicating that it is implicated in the renewal of the CLL clone, in keeping with other B-cell lymphomas where high EZH2 levels are correlated with a high proliferative index.