Figure 5. To measure the strain level that leads to keratin bundles adopting a wavy appearance, we loaded NEB-1 K14- GFP keratinocytes to increasingly greater maximal strains and took fluorescent images of the keratin network after the rubber substrate was returned to the unstrained state.

Average uniaxial cell strain reached is reported in the lower left corner each panel. Signs of network damage (arrowheads) appeared after cell strains as low as 50%, but became more widespread and obvious after cells were loaded to strains greater than 83%. Direction of stretch is indicated by the arrow in panel (A). Scale bar = 25 µm. (J) The tortuosity of bundles oriented parallel to the stretch axis increased significantly with the magntidue of uniaxial stretch to which the cells were subjected.