IL-8 release induced by allergenic extracts is dependent on p44/p42 MAPK. (A, B) The specific p44/p42 MAPK-pathway inhibitor, PD98059, inhibits HDMA- and GCA-induced IL-8 production. ELISA evaluated IL-8 production in cell culture supernatants from A549 cells. Cells were either previously treated or not treated with PD98059 (25 μM) before exposing to allergen extracts (HDMA or GCA) for 24 hours. Experiments were repeated and the results of a representative experiment is shown; *, p < 0.05; * *, p < 0.005; * * *, p = 3.6 × 10-5. (C) PD98059 inhibits the HDMA-induced phosphorylation of p44/p42 MAPK. A549 cells were preincubated with PD98059 (25 μM) before exposure to HDMA (25 μg/ml) for 10 min. Phosphorylation status of p44/p42 MAPK was evaluated by Western immunoblots from total cellular protein. Relative Intensity was calculated with ratios of densitometric quantifications bands from Phospho-MAP kinases and non-phosphorylated MAP kinases. The experiment was performed three times and a representative experiment is shown.