Next to the oncogenic potential of MLL rearrangement via ZNF521 or EVI1, which enhances AML transformation [7], NOTCH1 upregulation is known to be particularly relevant in lymphoid leukemia such as T-ALL or chronic lymphocytic leukemia (CLL) and is associated with a poor prognosis [35,36,37]. Here, ZNF521 is linked to B-cell chronic lymphocytic leukemia.