Fig. 3. Manipulation of the actin cytoskeleton by pathogens. (A) Arp2/3-based motility of pathogens. In contrast to Shigella and Listeria, the intracellular motility of Vaccinia and EPEC is dependent on the tyrosine phosphorylation of the pathogen-derived proteins A36R and Tir, respectively, and in addition involves the host cell Nck adaptor protein. (B) Structural mimicry in bacterial virulence. (C) Modifying bacterial protein toxins.