Effect of bortezomib treatment on NF-κB activation via TNF-α induction. (A) Histograms of IR values (x-axis) for 4-hour bortezomib treatment only (left column) versus 4-hour bortezomib treatment followed by 20 minutes of 10 ng/mL TNF-α treatment, over a range of bortezomib concentrations (y-axis is relative frequency [R.F.]). Red represents no treatment; and blue, treatments. (B) Representative images of RelA stains comparing bortezomib treatment only (left column) versus 4-hour bortezomib treatment followed by 20 minutes of 10 ng/mL TNF-α treatment. Scale bar represents 20 μm. (C) Dose-response curve of population mean IR, normalized to the population mean IR of the no treatment control (“IR Fold Increase” in graph). IC₅₀ ∼ 7.2nM bortezomib (n ≥ 3; independent averages of duplicates). Error bars represent SE.