Fig. 3. Inhibition of IL-8 induction by cell-penetrating peptides. (A) HeLa cells were incubated with medium containing the indicated peptides (40 µM) for 30 minutes at 37°C. After washing, cells were stimulated with TNF-R1-specific mutant TNF (100 ng/ml) for 5 hours (black bars) or left untreated (grey bars). IL-8 present in the supernatants as determined by ELISA was normalized on the cell number determined by MTT assay. (B) Cells were incubated with increasing concentrations of Antp or R9 for 30 minutes, stimulated with TNF-R1-specific mutant TNF (100 ng/ml) for 5 hours and IL-8 expression was determined. The error bars represent the standard deviation of the mean of three samples.