The effects of dominant-negative variants of FAK on adhesiveness of MCF-7 cells, surface expression and clustering of β1 integrins. (A) MCF-7 cells were stably transfected with dominant-negative mutant FAK constructs (FRNK, Y397F-FAK) or control vector, pcDNA3. The expression levels of endogenous FAK, FRNK and Y397F-FAK were determined by Western blot analysis using anti-FAK polyclonal antibody. (B) The effect of dominant-negative variants of FAK on CD98-induced cell adhesion rate was determined as described in Materials and Methods. In addition, whether addition of 0.5 µM Mn2+ interferes with the effect of PP2 on cell adhesion was determined by the same way. Results are expressed as in Figure 3 (B). *P < 0.05, **P < 0.01 (C) FAK variants- or mock-transfected MCF-7 cells were treatred with anti-CD98 mAb and secondary antibody and then analyzed for expression of β1 integrin through flow cytometry using FITC-conjugated anti-human β1 integrin. Results are expressed as in Figure 3 (C). Statistical comparisons are indicated by lines. **P < 0.01 (D) Confocal microscopy was performed as described above to investigate the effect of dominant-negative variants of FAK on clustering of β1 integrins. Scale bar, 50 µm. Original magnification, × 400.