REL and acute lymphoblastic leukemia: Bach2 is a lymphoid-specific transcription factor with a role in B-cell development36 and the response to oxidative stress.37, 38 Bach2 has also been identified as a tumour suppressor in acute lymphoblastic leukaemia.39 Importantly, quantitative PCR analysis confirmed that Bach2 mRNA expression is lost in B cells from 4-week-old Eμ-Myc/c-rel+/– and Eμ-Myc/c-rel–/– mice (Figure 3b), and also from the tumours taken from mice killed with end-stage disease (Figure 3c).