NFKB1 and influenza: In influenza-exposed cells, the lowest concentrations of toxins that triggered significant NF-κB/AP-1 activation were PVL 0.5 μg/mL (vs. 2.5 μg/mL in non-influenza-exposed cells), PSMα1 1 μg/mL (vs. 25 μg/mL), and PSMα3 5 μg/mL (vs. no activation) (Figure 1).