The epidermal growth factor-induced migration of rat liver epithelial cells is associated with a transient inhibition of DNA synthesis

Epidermal growth factor (EGF) is a potent mitogen for most cultured cells and has previously been shown to induce the migration of rat liver epithelial cells. We have now demonstrated that under migration-inducing conditions EGF does not stimulate cell proliferation, but causes instead a transient inhibition of DNA synthesis. Analysis at the single-cell level by [3H]thymidine autoradiography indicated that in 40–50% of the EGF-treated cell population the entry into S phase is delayed. The simultaneous demonstration of migration tracks by laminin immunofluorescence revealed that the transient inhibition of DNA synthesis is not restricted to the migratory cells. The effect is also observed with the stationary subpopulation and appears, therefore, to be independent of the induction of migration. The independence of both processes was further supported by showing that induction of migration by EGF proceeds undisturbed in cells blocked in S phase by aphidicolin. These results indicated that for rat liver epithelial cells the induction of migration by EGF has priority over cell proliferation. The data also emphasize the need for a time-course analysis when studying factors that stimulate or inhibit DNA synthesis or cell proliferation.