Isotropic increase in talin tension after uniaxial sustained stretch. (A) Schematic of uniaxial stretch device. Thick black arrow shows the direction of stretch. Black denotes the fixed part while the movable part is in gray. Yellow arrows indicate break pins for 10% stretch. (B) Photograph of stretcher with thin PDMS membrane and thick ring attached to create the well. (C) Representative FRET index map of talin-TS in FA in unstretched (left) and 10% stretched (right) membranes. The color bar represents the FRET index values where high FRET (red/white) indicates low tension while low FRET (blue) indicates high tension. White arrow shows the direction of stretch. Scale bars, 10 µm. (D) Histogram of mean FRET index per FA in unstretched and 10% stretched cells. Inset: Average FRET index normalized to the unstretched values for each experiment (n = 756 and 701 FAs from 48 and 36 cells in unstretched and 10% stretched state, respectively). (E) Plot of FRET index versus FA angle relative to direction of stretch for peripheral adhesions. Blue arrowhead indicates the direction of stretch (n = 830 peripheral FAs from 36 cells stretched by 10%). The purple line shows the smoothened plot obtained by 50-point adjacent averaging. FAs were categorized as parallel (0° ± 30°) or perpendicular (60° to 90° and −90° to −60°). (F) Histogram of mean FRET index per FA for perpendicular and parallel FAs in 10% stretched cells. Inset: Average FRET index normalized to perpendicular FAs within each experiment (n = 233 and 292 FAs for perpendicular and parallel FAs, respectively, from 36 cells). Four independent experiments gave similar results. Error bars represent SD.