Binding of Alexa488-labeled human α5β1 integrin to nadA-expressing yersiniae. 5 × 105 WA-c Δinv(pYV-nadA) (NadA-positive) or WA-c Δinv(pYV-SS) (NadA-negative, negative control) yersiniae were incubated with or without 1 μg of Alexa488-labeled human α5β1 integrin in PBS-0.2% Triton X-100 and 2 mm MnCl2 (5 μg/ml) for 1 h at 4 °C and analyzed by flow cytometry. A, histograms display the result from one representative experiment. a, WA-c Δinv(pYVO8-SS) without addition of Alexa488-labeled α5β1 integrin. b, WA-c Δinv(pYVO8-SS) with addition of Alexa488-labeled α5β1 integrin. c, WA-c Δinv(pYVO8-nadA) without addition of Alexa488-labeled α5β1 integrin. d, WA-c Δinv(pYVO8-nadA) with addition of Alexa488-labeled α5β1 integrin. Percents of Alexa488-positive events are displayed. B, Alexa488-positive events are expressed as the means ± S.E. of four independent experiments. *, p < 0.0416.