6H,H′ and data not shown). To visualize the cytoskeleton, we performed phalloidin staining ∼5 h after plating, when cells typically started to individually migrate. The cells of Dse-5MM-MO-injected CNC explants exhibited F-actin+ stress fibers throughout the cytoplasm, in addition to lamellipodia and filopodia at their leading edges (Fig. 6I). Dse-morphant cells only formed cortical networks of stress fibers below the membrane (Fig. 6J). The degree of cell spreading and percentage of cells that formed polarized protrusions were similar between the Dse-5MM-MO-injected and uninjected CNC explants, whereas the Dse-morphant cells had a 60% smaller surface and no protrusions (Fig. 6L,M). Importantly, Dse* mRNA restored the normal cell size and shape in the Dse-MO-injected CNC explants (Fig. 6K-M), which suggests that DS-epi1 is required for cells to spread and form polarized cell protrusions.
