FUR is subsequently converted to FUMP via uridine kinase (UK), which is then phosphorylated into fluorouridine diphosphate (FUDP) and further into the active metabolites fluorouridine triphosphate (FUTP) or fluorodeoxyuridine diphosphate (FdUDP) through ribonucleotide reductase (RNR) FUTP, a fluorinated RNA nucleotide analog, can be mistakenly incorporated into tumor cell RNA, causing RNA damage. This evidence concerns the gene UCK2 and neoplasm.