Figure 2.

(A) Mean sphericity index ($\psi$) for different cancer cells (RT112, T24 and J82) in various collagen gels (0.95 mg/mL to 1.8–4.5 mg/mL). *p < 0.05 (Kruskal Wallis test). Error bars represent mean ± SEM. (B) Mean major radius (R) of different cancer cells at low, intermediate and high collagen concentrations. (C) Graph representing contour fluctuations ($\nu$) vs. sphericity index $\psi$ . Insets show various shapes used by cancer cells of various invasiveness (blue for RT112 cells, green for T24 cells, red for J82 cells). (D) graph of contour fluctuations ($\nu$) vs. major radius (R) in μm. Solid line: power fit of $\nu$ = A + B * (R − C)${}^{1/2}$ with A = 10, 10, 10; B = 7.5, 10, 11; C = 14, 13, 11 respectively for J82, T24 and RT112 cells. (E) Migration speed (V) vs. contour fluctuations ($\nu$). Fits V = a*$\nu$ + b with a = 0.5, 0.25, 0.1 μm/h; b = 9.6, 7.3, 5.5 μm/h, for J82, T24 and RT112 cells.