Non-malignant rat liver epithelial cell line BRL was reported to adhere to a substrate by fibronectin. DNA synthesis of these cells was induced by adhesion to a substrate by fibronectin, while DNA synthesis in non-adhered cells was not observed. These results indicated that DNA synthesis in BRL cells is inducible by the cell adhesion signaling. Adhesion-inducible DNA synthesis was strongly inhibited by Herbimycin A. In contrast, vanadate showed the tendency to promote adhesion-inducible DNA synthesis. These results suggest that DNA synthesis caused by the cell adhesion in these cells was regulated by both phosphorylation and dephosphorylation at tyrosine residue. © 1995 by Academic Press, Inc.