TYMS and breast cancer: A moderate Ts depletion (Fig. 4a) did not affect proliferation (Supplementary Fig. 4D), as we had previously determined from breast cancer cell lines, that TS needs to reduce beyond a threshold to diminish proliferation.12 Furthermore, Ts knockdown also did not hamper the growth of primary tumours from the cells subcutaneously injected in flanks of syngeneic mice (Fig. 4b).