DUX4 and precursor B-cell acute lymphoblastic leukemia: Intriguingly, however, DUX4 expression was also much lower than Igμ in these B-ALL samples (the median FPKM 145.4 vs. 661.9, Fig. 1b)— raising an alternative possibility that IGH-DUX4 translocation might have instead occurred on the silenced IGH allele.