Fig. 8

Filament extension rate on the PDMS surface is slightly reduced compared to that in liquid media. a Filament extension rate on the PDMS surface is independent of stiffness and reduced compared to that in liquid media. The extension rate was determined as in Fig. 7c. Filament lengths of cells grown in serum-containing liquid media (n = 75–80 cells) were measured every 30 min with mean and SEM shown in red. Surface extension rates determined as in Fig. 7c (n = 30 cells; 3–9 experiments per PDMS stiffness). Bars indicate SD. The mean of all surface extension rates (dotted black line) and SEM (gray zone) are indicated. b Cells experience a resistive force on the PDMS surface. Invasive extension rates determined as in Fig. 7c (n = 53 cells; 5–10 experiments per PDMS stiffness) and normalized to surface extension rates, with bars indicating SD and dotted line the best fit. At Y = 1, X is ~ 20 kPa