Fig. 4: Cell mechanical anisotropy is strain dependent.

a schematic of stretching chamber, cells and their SFs aligned parallel (∥) and orthogonal (⊥) to the direction of stretch. \({\varepsilon }_{{{{{{\rm{x}}}}}}}\) indicated the applied strain, and \({\varepsilon }_{{{{{{\rm{y}}}}}}}\) the transverse compression from Poisson effect. b Images in RFP channel of TS, Y27632 treated and ML7 treated cells. Scale bar is 20 μm. c \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for TS parallel cells (∥), with 5%-20% applied strains. (n = 11 for 5%, n = 11, for 10%, n = 18 for 15% and n = 18 for 20% strains). One-way ANOVA was used for significance test. p(5% and 10%) = 0.7156, p(5% and 15%) = 0.1266, p(5% and 20%) = 0.0001, p(10% and 15%) = 0.0101, p(15% and 20%) = 0.0318. d \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for parallel CTS cells (∥). n = 10 for 5%, n = 10, for 10%, n = 12 for 15% and n = 7 for 20% strains. One-way ANOVA statistical significance with p-value = 0.7228 e \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for Y27632 treated parallel TS cells (∥). One-way ANOVA statistical significance with p-value = 0.0877 (n = 12 for 5%, n = 16, for 10%, n = 18 for 15% and n = 19 for 20% strains). f \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for ML7 treated parallel TS cells (∥)(n = 10 for 5%, n = 8 for 10%, n = 8 for 15% and n = 4 for 20% strains). One-way ANOVA statistical significance with p-value = 0.2683. g \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for orthogonal TS cells (⊥). (n = 29 for 5%, n = 22, for 10%, n = 7 for 15% and n = 20 for 20% strains). One-way ANOVA was used for significance test. p(5% and 10%) = 0.0142, p(5% and 15%) = 0.0278, p(5% and 20%) = 0.0268, p(10% and 15%) = 0.8749, p(10% and 20%) = 0.9671, p(15% and 20%) = 0.9899. h \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for orthogonal CTS cells (⊥) (n = 16 for 5%, n = 5, for 10%, n = 14 for 15% and n = 7 for 20% strains). One-way ANOVA statistical significance with p-value = 0.4127. i \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for Y27632 treated orthogonal TS (⊥) (n = 34 for 5%, n = 16, for 10%, n = 19 for 15% and n = 14 for 20% strains). One-way ANOVA test was used for significance test. p(5% and 10%) = 0.0219, p(5% and 15%) = 0.0160, p(5% and 20%)>0.99, p(10% and 15%)>0.99, p(10% and 20%) = 0.0772, p(15% and 20%) = 0.0690. j \(\Delta {{{{{\rm{FRET}}}}}}\) for ML7 treated orthogonal TS cells. n = 10 for 5%, n = 8, for 10%, n = 7 for 15% and n = 4 for 20% strains. One-way ANOVA was used for significance test. p(5% and 10%) = 0.0019, p(5% and 15%) < 0.0001, p(5% and 20%) = 0.0012, p(10% and 15%) = 0.2132, p(10% and 20%) = 0.7651, p(15% and 20%) = 0.9110. k FRET E histogram for cells undergoing relaxation and tensile response at 5% and 20% strains. l \(\Delta {{{{{\rm{FRET\; E}}}}}}\) as a function of \({\varepsilon }_{{{{{{\rm{x}}}}}}}\) and \({\varepsilon }_{{{{{{\rm{y}}}}}}}\) for parallel TS cells (∥). m \(\Delta {{{{{\rm{FRET\; E}}}}}}\) as a function of \({\varepsilon }_{{{{{{\rm{x}}}}}}}\) and \({\varepsilon }_{{{{{{\rm{y}}}}}}}\) for orthogonal TS cells (⊥). In all panels, data are presented as mean values ±SD. Source data are provided as a Source Data file.