KLF4 and acute myeloid leukemia: Interestingly, deletion of the KLF4 gene diminished cell growth and survival not only in this MLL-rearranged cell line, but also in NB4, a PML-RARα-rearranged cell line corresponding to the M3 subtype of AML, which express lower KLF4 levels compared to other AML cell lines [49, 50].