Fig. 4. (A) Collagen I-dependent cell adhesion. Equal numbers of cells were plated on collagen I-coated culture wells (U-bottom 96-well plates) for one hour at 37°C/5%CO₂. Cells were washed with PBS, fixed with 3.7% formaldehyde and stained with crystal violet (0.1% solution). Thereafter, cells were lysed in 20% acetic acid and values were determined at 570 nm in a plate reader. Values shown represent the mean of the values obtained from at least four independent experiments ± s.e.m. ^*P<0.001. (B) Cell spreading. Assay was performed as described in Materials and Methods. These photographs are representative of data from two independent clones for each transfected mutant molecule and at least four independent experiments. MDCK^5aa cells showed extended cellular extensions, whereas MDCK^con cells were all rounded. Original magnification x100. (C) Cell migration. Experiments were performed as described in Materials and Methods. Values shown represent the mean of the values obtained from at least four independent experiments ± s.e.m. ^*P<0.05; ^**P<0.001.