Fig. 5. Emergence of a process induced by the acute addition of laminin in the presence of CD is associated with actin. A growth cone labeled with fluorescent actin and growing on a polyamine substrate was treated with 125 nM CD for 15 minutes before exposure to laminin. Shown is a portion of the growth cone just before, and at indicated times after, the addition of laminin. Fluorescent actin (top row) and DIC images (bottom row) show the appearance of protrusions, which fuse and sprout a single filopodium. An intense focus of actin precedes a rapid elongation of the new process. Last panels show F-actin (phalloidin stain) and tubulin (immunocytochemical stain) in the same structure that was fixed at 27 minutes. Live actin staining is similar to F-actin staining. Tubulin is present and bundled in the shaft. Bar, 5 µm.