Over-expression of CTCF rescues the cell apoptosis and proliferation induced by an NF-κB activity inhibitor. (A) Nalm-6 cells were treated with the NF-κB inhibitor PDTC or DMSO for 20 h before transient transfection with the over-expressing plasmids. Cellular apoptosis was assessed by flow cytometry analysis of Annexin V-APC/PI staining at 48 h after transfection. The percentages of cells in early apoptosis [Annexin V (+)/PI (-)] and late apoptosis [Annexin V (+)/PI (+)] are indicated in the figure, respectively. (B) The percentage of cell apoptosis (both early and late apoptosis) in each group is indicated in the diagram as mean ± SD from three independent experiments (**p = 0.000). (C) Clones over-expressing CTCF were seeded in a 96-well plate at 1 × 104 cells per well, with three replicates per clone. Viable cells were counted using the CCK-8 assay for 5 days. (D) Caspase-3 activation and the expression levels of the transfected plasmids were measured by Western blot.