<prompt> The mechanism of anti cancer action of fluoruracil isCross linking of double standard DNA and the resulting inhibition of DNA replication and transcriptionCytotoxicity resulting from metabolite that interferes with the production of dTMPIrreversible inhibition of dihydrofolic acid reductaseSelective action of DNA polymerase  <response>: 5-FU is an antimetabolite.it us a thymidine analogue and acts by conversion to 5-dUMP .latter inhibits the formation of dTMP and result in Thymineless dealth of cells Ref-KDT 6824 