the 5-fluorouracil-resistant lines were found to ( a ) have an auxotrophic requirement when grown in dialyzed fetal calf serum that was satisfied by the addition of either thymidine , deoxyuridine , or deoxycytidine to the medium , ( b ) be cross-resistant to the toxic effects of 1-beta-d-arabinofuranosylcytosine and to high concentrations of thymidine , ( c ) have increased intracellular levels of cytidine 5'-triphosphate ( ctp ) and deoxycytidine 5'-triphosphate and decreased levels of uridine 5'-triphosphate , ( d ) also be resistant to 5-fluorouridine but not to 5-fluorodeoxyuridine , and ( e ) incorporate less 5-fluorouracil into rna than do the wild-type cells .
C0011535
deoxyuridine
C0016343
fluorodeoxyuridine