Fig. 4. The ₁ß₁ integrin has a major role for fibroblast adhesion to collagen IV and laminin 1, and to a lesser extent to collagen I. Wild-type and ₂-deficient mouse fibroblasts were seeded on wells coated with collagen I, collagen IV, laminin 1 and laminin 5, as indicated, in the absence (-) or the presence of function-blocking antibodies (20 µg/ml) against integrin ₁, ₂ and ß₁ subunits. After 30 minutes of incubation, the extent of cell adhesion was determined as in Fig. 2. The results were expressed as a percentage of the control without antibodies set as 100%.