FIGURE 1.

Host protein-tyrosine kinase activity is required for PspC-hpIgR-mediated invasion of pneumococci into MDCK-hpIgR and Calu-3 cells. A and B, invasion and intracellular survival of the bacteria in MDCK-hpIgR and Calu-3 cells was monitored in the absence (Ctrl) or presence of the broad spectrum protein-tyrosine kinase inhibitor genistein (50 μm) or Src family of tyrosine kinase inhibitor PP2 (5 μm) by a antibiotic protection assay. Pneumococcal invasion in the absence of the inhibitors was set to 100%. *, p < 0.001 relative to infections carried out in the absence of inhibitor. C and D, pneumococcal adherence to MDCK-hpIgR and Calu-3 cells was determined in the absence (Ctrl) or presence of genistein or PP2. Adherence of S. pneumoniae in the absence of an inhibitor was set to 100%.