Fig. 12. Proposed signaling model. Chemotaxis involves three signals that, together, direct the cell towards a site of infection. The first of these signals is generated by p38 MAPK, and allows a cell to `ignore' intermediary chemoattractants (a). The second signal is an inside-out signal, generated by the chemoattractants, which results in the activation of the integrins (b). Lastly, a signal is generated by integrin-ligand interactions, and provides outside-in signals that are required to `steer' the cell (c). Lines with arrow heads at the ends represent stimulatory pathways. Lines with bars at the end represent inhibitory pathways.