USF2 and leukemia: To examine if USF2 regulation of HOXA9 expression was unique to MLLr leukemias, we used two sgRNAs, sgUSF2#2 and sgUSF2#3, to knockdown USF2 expression in two human non-MLLr leukemia cell lines, OCI-AML3 and U937, which both express HOXA9. Upon complete USF2 depletion, HOXA9 expression remained unchanged, suggesting the USF2/HOXA9 axis may function in a MLLr-dependent manner (Figure 5—figure supplement 2A-D).