The transcellular cytokeratin (CK) network in keratinocytes of the skin bears high loads of mechanical stress. We addressed the question up to which stretch magnitude the CK network responds without sustained damage and how the cells handle CK-fiber overextension. Moreover, we investigated the effect of protein phosphorylation on stretch induced changes of the CK-network. With a computer controlled stretch device we stretched SCC-25 cells by 10%, 20%, 40%, 60% and 80% for 5 seconds and then released the stretch. We used CK18-YFP, immunofluorescence and electron microscopy to compare the CK-filaments before and after relaxation of the stretch. No apparent differences were observed after stretch amplitudes up to 20% whereas higher stretch amplitudes overextended the CK-network leading to wavy CK-filaments when stretch was released. The required net increase of CK-fiber length to explain this effect was caused by both, overextension of individual CK-fibers as well as a stretch-induced disruption of the entire CK network. Kinase inhibitors (to lesser degree also phosphatase inhibitors), dramatically reduced the stretch magnitude necessary to overextend the fibers. Interestingly, some CK fibers regained a taut appearance within 10–20 min after relaxation and we are currently investigating the mechanism of this recovery process. We conclude that elasticity of CK fibers can be modulated by phosphorylation and even an apparently overextended CK network can recover to a certain degree. This might be relevant for diseases related to CK-fiber mutations or hemi/-desmosomal detachment. Moreover our extendable skin model might help to detect subtle, stretch induced effects in diseased skin.