One of the mechanisms involved in 5-FU of CRC is increasing themRNA levels of thymidylate synthase (TS), the target of 5-FU.38 CRC presented intrinsic higher levels of mRNAand accumulation of TS in vitro, in vivo, and in patients.39 This informationhas been used to direct new ways of treating CRC. Here, TYMS is linked to colorectal carcinoma.