Invasive phenotype emerged in a sub-population of irradiated MCF10A-Akt cells are associated with nuclear translocation of NF-κB. (A) On Day 30 cultures, immunoblotting of nuclear fraction shows up-regulated nuclear translocation of NF-κB p65 in the 8 Gy IR cultures. The intensities of NF-κB were normalized with nuclear protein, Histone H1 (**, P < 0.01, n = 4). (B) IF images of confocal microscopy show β1-integrin (green), NF-κB (red) and nuclei (blue). Bar = 50 μm. (C) The binding of NF-κB to the β1-integrin promoter region is up-regulated in MCF10A-Akt cells that survived after exposure to radiation (WT, wild-type, Mt, mutated oligonucleotide; n = 3, *, P < 0.05). (D-E) The NF-κB inhibitor, JSH-23, was added from day 0 of the second three-dimensional cultures. IR-induced chemoinvasion activity, which was inhibited by NF-κB inhibitor, JSH-23. Bar = 50 μm. IF, immunofluorescence; IR, ionizing radiation; NF-κB, nuclear factor-kappaB; TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.