Figure 2.

Model 1 Predictions: Cell Area Increases with Increasing Substrate Stiffness

(A) Example configurations of cells at 2000 MCS on substrates of 1, 50, and 50 kPa.

(B) Cell area as a function of substrate stiffness, shaded regions: standard deviations over 25 simulations.

(C and D) (C) Time-series of cell area, shaded regions: standard deviations over 25 simulations; and (D) distribution of N, the number of integrin bonds per cluster, all clusters at 2000 MCS from 25 simulations were pooled. We indicate the median. Color coding (C and D): see legend next to (D).

(E) A cartoon to schematically explain spreading of a cell based on our model. Top: cell on a soft substrate; bottom: cell on a stiff substrate. The cell forms protrusions (cyan) that either successfully get stuck to the ECM or are retracted. The cell starts to build up a force, which builds up much faster on stiff substrate. Thus, on stiff substrates, FAs stabilize. Because the counteracting adhesive force is too small, the cell retracts from the soft substrate, whereas the cell is able to stick and spread further on a stiff substrate.

See also Video S1, Table S2, Figures S1, S4A, and S5.