Induction of cagA, fliA, and flaA in chemotaxis mutants of Helicobacter pylori. Expression of cagA, fliA, and flaA in unadhered and AGS-adhered wild-type (WT), ΔtlpB, and ΔcheA strains was examined by quantitative reverse transcription polymerase chain reaction analysis. Transcript levels are expressed relative to that in the unadhered WT strain, arbitrarily taken as 1. The bar diagram represents the mean value ± standard deviation (SD) of at least 3 experiments. Error bars represent SDs. The statistical significance (P values) of the differences in gene expression between AGS-adhered and unadhered H. pylori strains are indicated. *P ≤ .05 and **P ≤ .01.