Upon forced overexpression, the WT1 protein interferes with differentiation of myeloid cell lines [18–20] and cooperates with the fusion protein RUNX1/RUNX1T1 (AML1/ETO) in a rapid induction of leukemia in transgenic mice, clearly demonstrating a leukemogenic role for WT1 [21]. Here, RUNX1T1 is linked to leukemia.