TS is a rate-limiting enzyme in the synthesis of the thymidine and converts dUMP into dTMP, the only source of thymidine for DNA synthesis and repair. Thus, TS plays an important role in the cell division and proliferation. TS是合成胸苷酸的限速酶,催化dUMP转化为dTMP,而dTMP是DNA合成和修复所必须的胸腺嘧啶核苷酸的唯一来源,所以TS在细胞增生过程中发挥重要作用。