Tegafur (FT 207; NSC 148958) is a chemotherapeutic 5-FU prodrug used in the treatment of cancers; is a component of tegafur-uracil. IC50 & Target: Nucleoside antimetabolite/analog In Vitro: Tegafur is bioactivated to 5-FU by liver microsomal cytochrome P450 enzymes. 5-FU is subsequently converted into its active metabolites 5-fluoro-deoxyuridine-monophosphate (FdUMP) and 5-fluorouridine-triphosphate (FUTP) intracellularly; these metabolites inhibit the enzyme thymidylate synthase and intercalate into RNA, resulting in decreased thymidine synthesis, reduced DNA synthesis, disrupted RNA function, and tumor cell cytotoxicity.