Fig. 3. Integrin 3ß1 is localized at leading lamellipodia and its adhesion to LN-5 is required for lamellipodia formation by wound-edge cells. (A,B) MK3 cells were grown to confluence on collagen-coated glass coverslips, wounded, fixed 2 hours after wounding and then stained with P1B5 for 3ß1 integrin (B); the corresponding phase-contrast image is shown in (A). Arrowheads point to lamellipodium edge. Bar, 10 µm. (C) P1B5 staining of the MK3 monolayer away from the scrape wound shows the expected cell-cell localization of 3ß1. (D) Confluent MK^–/– cells show a lack of staining with P1B5. (E) MK3 cells on collagen-coated surfaces were scrape wounded and photographed immediately after wounding (0 hours) or 2 hours after wounding in the presence of a control IgG, a function-blocking antibody against integrin 3ß1 (P1B5) or a function-blocking antibody against integrin 6ß4 (GoH3), as indicated. Bar, 100 µm. (E') Panels show close-up images of wound-edge cells from IgG-treated or P1B5-treated scrape wounds, as indicated. (F) The proportions of leading-edge cells displaying lamellipodia were determined for three separate wound edges, 60 cells for each wound edge. Error bars represent s.e.m.