Fig. 8.

Increased contractile force generation of α5β1^high cells and inhibition of contractile-force-mediated cell invasion. (A) Representative traction fields of a α5β1^low cell (left) and α5β1^high cell (right). The gray line represents the cell boundaries. The insets show a bright field image of the measured cells. (B) The strain energy per cell (mean + s.e.m.) of α5β1^high cells (n=80) was increased sevenfold compared to α5β1^low cells (n=84). (C) Modulation contrast images of adherent cells on top of collagen gels (top row) or after 3 days of gel invasion (bottom row) show no morphology changes after treatment with myosin contraction inhibitors ML-7 or Y27632. (D) Percentage (mean + s.e.m.) of invasive α5β1^high cells or α5β1^low cells determined after 3 days in the presence of 100 μM Y27632, 15 μM ML-7 or DMSO as control. (E,F) Invasion profiles of α5β1^high (E) and α5β1^low (F) cells treated with Y26732, ML-7 or DMSO as control. (G) Percentage of invasive cells (mean ± s.e.m.) of α5β1^high or α5β1^low cells was determined after 3 days in the presence of actin polymerization inhibitor (2 μM latrunculin B), myosin phosphatase inhibitor (1 nM calyculin A) or DMSO as control. (H,I) Invasion profiles of α5β1^high (H) and α5β1^low (I) cells treated with latrunculin B, calyculin A or DMSO as control. (J) The use of serum-free medium (SF) did not alter the percentage of invasive cells. (K) Serum-free conditions reduced the invasion depths of invasive α5β1^high cells but not α5β1^low cells. *P<0.05, ***P<0.001. Scale bars: 20 μm.