Fibronectin receptors are functional on mitotic Chinese hamster ovary cells

In this paper, evidence is provided indicating that the blockade of presynchronized CHO 15B cells in prometaphase by nocodazole is fully reversible and efficient enough to allow us to analyze the function of the integrin receptors. Flow cytometry analysis using a specific antibody raised against the fibronectin receptor, and binding studies of the radiolabeled fibronectin on the cell membrane, indicated a stable number of receptors at the cell surface during mitosis. Furthermore, in the mean time, only a slight increase in the Kd value of the fibronectin-receptor interaction was detected. A binding assay designed to test the affinity of the receptor for its extracellular ligand in an insoluble form was used. No difference was observed between mitotic and interphasic cells. Taken together, these results indicate that the rounding up of the cells observed during mitosis is not due to a loss of the receptor affinity for its extracellular ligand.