ARID4B and acute lymphoblastic leukemia: These competition assays were performed in the KMT2A-r ALL cell lines SEM and in the KMT2A-w BCP-ALL cell lines 697, using both sgRNAs derived from our original screening libraries as well as with commercially available sgRNAs with high efficiency and low off-target effects (i.e., ARID4B_IDT_1AA, MBD3_AB, and MBD3_AC).