IL-17 increases the half life time of Nfkbiz mRNA by modulating RNA stability. (A) Cells were incubated with actinomycin D (5 μg/ml) to stop further transcription and Nfkbiz mRNA levels were determined after the indicated times. To calculate the RNA half life time (34.36 minutes) results were expressed as % remaining RNA over time and one phase decay curves were applied. (B) Influence of cytokines was tested by incubation of primary hepatocytes with IL-17 (100 ng/ml) for 30 minutes with or without additional TNF-α (2 ng/ml) stimulation or TNF-α alone. Then actinomycin D was added and cells were further incubated for the indicated times. Nfkbiz mRNA levels were determined and plotted and analyzed as described above. RNA half life time was calculated and shows a remarkable increase up to 87.26 minutes induced by IL-17 and 80.47 minutes by IL-17/TNF-α compared to 24.56 minutes induced by TNF-α treatment alone. Data represent means +/- SD of at least three independent experiments.