Figure 2.

Vimentin loss decreases internal cell elastic modulus. AFM indentation of normal (black) or vim^−/− mEF (gray) spread to 2,500–4,000 μm² on 6 kPa PAA (A; average E at 600 nm; 6 kPa, mEF 1,253 ± 589 Pa, n = 67 and vim^−/− 1494 ± 374, n = 53) or TCplas (B; TCplas; mEF 1833 ± 329, n = 58 and vim^−/− 1959 ± 209, n = 45; p < 0.05; error = SD; min 3 experiments) show no difference in the Young’s moduli of the two cell types on either substrate, but a significant difference between either cell type on the soft compared to the stiff substrate. Insets show curve fits (solid lines) and 95% confidence intervals (dashed lines) for the same data, unbinned. Unlike less-spread cells, maximally spread normal mEFs are stiffer than vim^−/− mEFs (C; average E at 600 nm; mEF 3512 ± 1479 Pa and vim^−/− 2855 ± 1287, p < 0.02; n = 46; error = SD). Furthermore, both cell types are stiffer when maximally spread than when less spread on TCplas. As a control, 6 kPa PAA gels were indented in regions devoid of cells (D; n = 30; error = SD).