KLF4 and acute lymphoblastic leukemia: Interestingly, most T-ALL samples showed insertion/deletion of nucleotides in the region corresponding to the third zinc-finger (Zf3) motif of KLF4, while deletion of nucleotides in the first zinc-finger (Zf1) motif was identified in some T-ALL samples (Figure 3D, Additional file 1: Figure S1).