Importance of the CadF and flagellar apparatus for C. jejuni -induced activation of Cdc42 and bacterial invasion. (A) FAK+/+ and FAK-/- cells were infected with wt C. jejuni F38011 or isogenic F38011ΔcadF for the indicated periods of time. Quantification of Cdc42-GTP levels by CRIB-GST pulldown during the course of infection. One hundred % of activity corresponds to the highest amount of detected Cdc42-GTP level (lane 4). ( B) FAK-positive cells were infected with the indicated strains in a time-course. The presence of bound, active Cdc42-GTP was analyzed in CRIB-GST pulldown assays followed by Western blotting using α-Cdc42 antibody. Similar quantities of individual GTPases at every time point were confirmed by Western blotting using equivalent volumes of cell lysates. (C) Quantification of Cdc42-GTP levels during the course of infection. One hundred % of activity corresponds to the highest amount of detected Cdc42-GTP level (lane 3). The amount of intracellular bacteria was quantified by gentamicin protection assays under the same experimental conditions. (**) P ≤ 0.005 were considered as statistically significant as compared to the control.