Formation of stress fibres and focal adhesion sites in monensin-exposed cultured human fibroblasts in response to exogenously added cellular fibronectin.

Human fibroblasts, plated and cultured in serum-free conditions in the presence of monensin, a carboxylic ionophore, attach and attain a flattened morphology, although fibronectin deposition does not take place. They fail, however, to develop organized stress fibers, vinculin plaques, and focal adhesion sites. In the present study, we demonstrate that the actomyosin-vinculin system of the monensin-exposed cells can be restored by plating the cells on the culture substratum coated with cellular fibronectin. Direct overlay of the electrophoretically separated polypeptides of the cultured fibroblasts with iodinated fibronectin revealed several polypeptides which could represent putative cell-surface receptors for fibronectin.