Increased Thymidylate Synthetase Activity in 5-Fluorodeoxyuridine-Resistant Novikoff Hepatoma Cells

Abstract
A fluorodeoxyuridine resistant Novikoff [rat] hepatoma cell line, which was previously characterized as being thymidine kinase deficient, had elevated levels of thymidylate synthetase. The thymidylate synthetase activity in the fluorodeoxyuridine-resistant cell line was sensitive to inhibition by FdUMP [fluorodeoxy-UMP] to the same extent as the fluorodeoxyuridine sensitive cell line.