KLF4 and acute lymphoblastic leukemia: Epigenetic silencing of the KLF4 gene, an alternate mechanism that may be responsible for the low expression of KLF4 in ALL cells, was supported by the 8-fold (KOPTK1), 13-fold (RMPI), 6-fold (DND41), and 5-fold (Jurkat) increases of KLF4 expression upon culture of the leukemic cells in the presence of 5-azacytidine (not shown).