||P.549 bottom paragraph: "This is a minimal model with just 5 of the >60 families of actin-binding proteins (ref 101). [Investigators] focus on these proteins (profilin and thymosin-β4, Arp2/3 complex, capping protein, and ADF/cofilin), because they are highly conserved, well characterized, and sufficient to induce self-sustaining assembly of dynamic actin filament networks that drive motility of pathogenic, intracellular bacteria (ref 63). Most eukaryotic cells use the same abundant set of cytoskeletal proteins to construct pseudopods (Table 1). Yeasts have similar proteins in dynamic actin patches. Because the building blocks, the overall structure, and (probably) the mechanism of assembly are so highly conserved, [they] regard the leading edge of a motile cell as a discrete cytoskeletal structure, one whose function and design principles were specified early in eukaryotic evolution."