IRF4 and B-cell chronic lymphocytic leukemia: We focused our attention on determining the expression of Notch2 protein in +12 and no +12 CLL cells, and we observed that +12 CLL cells with high expression of IRF4 are characterized by a significant increased expression of Notch2 compared to no +12 (Figure 1A; n = 8, *p < 0.05, **p < 0.01).