KLF4 and acute lymphoblastic leukemia: MiR-2909-mediated down-regulation resulted in loss of KLF4 (isoform 1) activity in B-ALL as opposed to T-ALL where miR-2909 was unable to regulate KLF4 expression in T-ALL (isoform 2), due to mutations in KLF4 3'UTR, which includes the miR-2909 binding site [48].