Importance of fibronectin, integrin-β1, FAK and Src kinases expression on C. jejuni invasion. The following cells lines were infected with wt C. jejuni 81-176 for 6 hours. (A) Fibronectin-deficient cells (Fn-/-) and corresponding floxed wt cells (Fn+/+), (B) integrin-β1-deficient cells (GD25) and GD25 stably re-expressing wt integrin-β1A (GD25-β1A) cells, (C) FAK-deficient cells (FAK-/-) and FAK-/- cells stably re-expressing wt FAK and (D) Src kinase-deficient cells (SYF-/-) and SYF-/- cells stably re-expressing wt c-src. Intracellular C. jejuni were quantified by gentamicin protection assays, and Cdc42 activation by CRIB-GST pulldowns. (**) P ≤ 0.005 was considered as statistically significant. Fibronectin, integrin-β1, FAK and Src expression was analyzed by immunoblotting. GAPDH expression levels were determined as loading control.