IRX1 and acute lymphoblastic leukemia: Western blot analysis showed expression of IRX1, IRX2, IRX3 and MEIS1 in selected BCP-ALL cell lines at the protein level (Figure 3), while RT-PCR analysis confirmed the presence of particular fusion genes (Figure S5), demonstrating that these cell lines are suitable models for examining the role of aberrantly expressed TALE homeobox genes in according BCP-ALL subtypes.