FIGURE 8.

Protein-tyrosine kinase activities and PI3K but not small Rho family GTPases are essential for Factor H-mediated pneumococcal ingestion by epithelial cells. The number of invasive pneumococci was determined in the presence of genistein (A), which is a phosphotyrosine kinase inhibitor, PI3K inhibitor wortmannin (B), C. difficile toxin B, TcdB10463 (30 ng ml⁻¹) (C), or specific individual inhibitors of Rho family GTPases such as Y27632 (50 μm), Rac1 inhibitor NSC23766 (50 μm), or Cdc42 inhibitor secramine A (10 μm) (D) by employing the antibiotic protection assay. Shown is the relative invasion of Factor H pretreated or untreated (none) pneumococci in the presence of an inhibitor compared with pneumococcal invasion in the absence of an inhibitor. *, p < 0.05; ns, not significant, relative to infections in the presence of Factor H but absence of inhibitors.