C. jejuni invasion is impaired in cells expressing integrin-β1 point mutations exhibiting defects in fibronectin fibril organisation or FAK phosphorylation. (A) Integrin-β1-deficient cells (GD25) and GD25 stably re-expressing mutated integrin subunit β1A (GD25-β1 ATT788-9AA or GD25-β1 AY783/795F or wild-type β1A (GD25-β1A) cells were infected with wt C. jejuni 81-176 for 6 hours. Intracellular C. jejuni were quantified by gentamicin protection assays. (B) The presence of active Cdc42-GTP was quantified by CRIB-GST pulldowns. One hundred % of activity corresponds to the highest amount of detected Cdc42-GTP level. (**) P ≤ 0.005 was considered as statistically significant. Similar quantities of total Cdc42 and GAPDH were confirmed by Western blotting.