Fig. 3. Polarization on collagen requires interactions of integrin 3ß1 with precursor laminin 5 deposits. Cells were plated onto exogenous laminin 5 (A,B) or collagen (C-F) in the absence of antibody (C) or the presence of anti-2 mAb P1H5 (A), anti-3 mAb P1B5 (D), anti-6 goH3 (G) or anti-laminin 5 mAb C2-9 (E) for 5 hours then the percentage of polarized cells were determined (see Materials and Methods). Alternatively, for those antibodies that would block initial adhesion, cells were instead plated for 1 hour to allow for adhesion and spreading prior to the addition of anti-3 mAb P1B5 (B) or anti-2 P1H5 (F) for 3 hours before cells were quantified. (G) Summary of data obtained from polarization experiments. Values represent the average and standard deviation of at least three independent experiments.