Fig. 4. Coordinated localization of fibronectin, actin stress fibers, ß1 integrin and coimmunoprecipitation of ADAM12 and ß1 integrin. Immunostaining of fibronectin (A), F-actin (B) and ß1 integrin (C) in growing LiSa-2 cells. Fibronectin staining outside the cells and actin stress fibers inside the cells are parallel to each other, with the cell-surface ß1 integrin receptor localized at the matrix points. (D) Co-immunoprecipitation of ADAM12 and ß1 integrin from cell extracts of LiSa-2 (lane 3), C3H10T1/2 (lane 5) and 3T3-L1 (lane 7) cells. For this experiment, cell extracts were immunoprecipitated with monoclonal antibodies to ADAM12 (lanes 3,5,7) or control IgG (lanes 2,4,6), and complexes were examined by western blotting with monoclonal antibodies to human ß1 integrin JB1A (lanes 2,3) and to mouse ß1 integrin clone 18 (lanes 4-7). Lane 1 is a direct western blot of ß1 integrin in LiSa-2 cell lysate using the JB1A monoclonal antibody. Bar, 6 µm.