Allergenic extracts from GCA and ACA induced phosphorylation of p44/p42 MAPK. Following exposure of A549 cells to GCA (25 μg/ml) and ACA (25 μg/ml) at indicated time points, total protein extracts were evaluated by western immunoblotting with antibodies specific for phosphorylated and non-phosphorylated p44/p42 MAPK. Phospho-p44/p42 MAPK bands were quantified by densitometry and normalized to p44/p42 MAPK levels of intensity. The experiment was repeated twice. A representative experiment is shown.