Figure 1: U251 cells respond heterogeneously to a proinflammatory trigger. (a) Immunocytochemistry of the NF-κB subunit p65 (magenta) shows nuclear translocation of NF-κB after stimulation with TNFα for 15 min (arrowheads). Note the heterogeneous response in p65 nuclear translocation in U251 cells (asterisk). Scale bar: 100 μm. (b) Quantification of nuclear p65 intensity showed significant increase of nuclear translocated NF-κB in TNFα-treated U251 cells compared to untreated U251-cells. Data are presented as mean ± SD from three different measurements (merged), compared using Student’s t-test (unpaired, two-tailed, CI 95%). . (c) Increased relative luciferase activity was observed in U251 cells transiently transfected with a NF-κB-dependent luciferase reporter. Mean ± SEM from three different experiments are shown, analysed using unpaired Student’s t-test (two-tailed, CI 95%). . (d) Schematic display of the lentiviral NF-κB-dependent luciferase reporter. NF-κB activation leads to binding of NF-κB to respective response elements, enhancing GFP and luciferase reporter gene expression through activation of the minimal CMV promoter.