Demonstration of cross-linked cytokeratin polypeptides in transplantable rat hepatoma cells

Covalently cross-linked multimers of cytokeratins were shown to be present in transplantable Morris hepatoma 7777 cells. These high molecular weight antigens were not detectable in normal rat liver cells. However, identical high molecular weight antigens were also demonstrated in rat liver cells when the cells were homogenized in solutions containing Ca2+. The cross-linking reaction was suggested to be mediated by the action of tissue transglutaminases.