Calu-3 human lung epithelial cells were seeded onto 6-well plates and grown to about 80% confluency. Epithelial monolayers were infected with 10**8 CFUs per ml of one of the bacterial strains (FRD1, FRD440, FRD875, or FRD1234) for 60 min and then washed extensively with phosphate-buffered saline. The cultures were subsequently incubated in fresh RPMI 1640 medium supplemented with 10% fetal bovine serum and 100 µg/ml gentamicin. After 6 h, total RNA from the cells was prepared with RNAzol and further purified with RNEasy (Qiagen) for microarray hybridization. Control samples of Calu-3 cells were treated similarly, but not infected with bacteria. Single array image analysis was performed using MAS 5 (Affymetrix) to derive probeset intensities and detection p-values. All arrays were globally scaled to 500. Keywords = CF, Cystic Fibrosis, Pseudomonas, Alginate, Flagellin