MII inhibition alters GEF localization. Cells expressing GFP-βPIX (green, right) and plated on fibronectin for 2 h were treated with 50 µM blebbistatin (Blebb) for the indicated time points, stained for actin (red) and pY118-paxillin (blue), and imaged using a confocal microscope (FV1000; Olympus). Arrowheads point to retraction defects; arrows point to the GEFs. Note the relatively even distribution of βPIX in the Blebb-treated cells. Color insets: detail (enlarged from the boxed regions) of the thin actin-rich band near the leading edge, where βPIX and paxillin phosphorylation (Y118) are more prominent. Bar, 10 µm.