Altered accumulations of fibronectin are not dependent on fibronectin modifications during the differentiation of F-9 teratocarcinoma stem cells.

F-9 teratocarcinoma stem cells differentiate into parietal endoderm when monolayer cultures are treated with retinoic acid. This change in phenotype is accompanied by increased accumulation and altered organization of fibronectin deposits. Although both stem cells and treated cells synthesize and accumulate fibronectin, only the treated cells deposit a fibrillar array of the protein. We have monitored the accumulation of fibronectin in nontreated and treated F-9 cells with indirect immunofluorescence and have biochemically analyzed the fibronectin synthesized by each cell type with one- and two-dimensional acrylamide gels and peptide maps. Our data suggest that no differences exist between these fibronectins to account for the observed changes in accumulation. Thus, another mechanism may regulate the organization of matrix deposition.