Effects of keratin phosphorylation on the mechanical properties of keratin filaments in living cells.

Keratin filaments impart resilience against mechanical extension of the cell. Despite the pathophysiological relevance of this function, very little is known about the mechanical properties of intermediate filaments in living cells and how these properties are modulated. We used keratin mutants that mimic or abrogate phosphorylation of keratin 8-serine(431) and keratin 18-serine(52) and investigated their effect on keratin tortuousness after cell stretch release in squamous cell carcinoma cells.