The LINC complex and lamin A regulate cell contractility and migration in response to substratum rigidity. (A) Cell velocity ± 95% CI on compliant substrata for REF52 cells treated with siCntl (n ≥ 118/stiffness), siSun1/Sun2 siRNA pair 1 (n ≥ 71/stiffness), and siSun1/Sun2 siRNA pair 2 (n ≥ 42/stiffness). (B) Contractile energy of REF52 cells treated with siCntl (n = 139), siSun1/Sun2 siRNA pair 1 (n = 117), and siSun1/Sun2 siRNA pair 2 (n = 97). (C) Mean traction stress ± SEM for siCntl and siSun1/Sun2–treated REF52 cells. (D) Cell velocity ± 95% CI on compliant substrata for Lmna^+/+ (n ≥ 79/stiffness) and Lmna^−/− (n ≥ 113/stiffness) cells. (E) Contractile energy of Lmna^+/+ (n = 90) and Lmna^−/− (n = 103) cells. (F) Mean traction stress ± SEM for Lmna^+/+ and Lmna^−/− cells. (G) Cell velocity ± 95% CI on compliant substrata for Lmna^−/− cells rescued with lamin A (n ≥ 69/stiffness) or mock (n ≥ 67/stiffness). (H) Contractile energy of Lmna^−/− cells rescued with lamin A (n = 117) or mock (n = 106). (I) Mean traction stress ± SEM for Lmna^−/− cells rescued with lamin A or mock. (J) Cell velocity ± 95% CI on compliant substrata for untreated intact REF52 cells (n ≥ 92/stiffness) or in the presence of 15 µM (n ≥ 74/stiffness) or 50 µM (n ≥ 60/stiffness) bleb. Dotted lines in A, D, G, and J show 8 and 25 kPa. All data are from at least three independent experiments. One-way ANOVA with Tukey’s post-hoc test was performed between stepwise increases in stiffness for A, D, G, and J. The Kruskal–Wallis test with Dunn’s multiple comparisons was performed for B and C. The Mann–Whitney U test was performed for all other traction force data. Boxplots show 10th–90th percentiles. ***, P < 0.001; **, P < 0.01; *, P < 0.05.