SH2-Bβ enhances Listeria motility in Xenopus egg extract. (A) Listeria cells were incubated in Xenopus egg extracts supplemented with rhodamine-labeled G-actin and either GST or GST-SH2-Bβ. Large arrows indicate the initial position of the bacterium, and thin arrows indicate the moving bacterium. Bar, 8 μm. (B) The movement of bacteria versus time was measured, and the velocity was calculated. Bars represent means plus SEM (n = 8, 12, and 17 for extracts without supplementation and those supplemented with GST and GST-SH2-Bβ, respectively). *, P < 0.05 compared to extracts supplemented with GST.