TYMS and cancer: For example, thymidylate synthase inhibitors, such as 5-fluorouracil (5-FU) or 5-fluorodeoxyuridine (5-FdUrd), are widely used in cancer therapies [24,25,26] and the first dUTPase inhibitors are undergoing detailed investigations [23,27,28,29,30,31,32,33,34].