AFF1 and acute myeloid leukemia: MV4-11 cells, a human-derived AML cell line homozygous for the FLT3-ITD mutation [13] and positive for the fusion protein MLL-AF4 [14], were transduced with the lentiCRISPRv2 library at ~250X coverage and an MOI of 0.3 to favor single viral integrations.