5-Fluorouracil (5-FU) is still a key drug in the treatment of various kinds of advanced cancer, including breast and gastrointestinal carcinomas. To predict the sensitivity of colorectal cancer to 5-FU, mRNA is extracted from surgically obtained cancer specimens and expression of thymidylate synthetase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), uridine phosphorylase (UP), es-nucleoside transporter (NT), and E2F1 are detected by real-time reverse transcription polymerase chain reaction (RT-PCR) (TaqMan�). Previous results have shown that the catabolic rate-limiting enzymes DPD and NT, which are important membranous transporter of nucleosides, may regulate the sensitivity to 5-FU.
