Knockdown of ASCT2 or SPOP markedly inhibited or promoted cell growth and clonogenic survival, respectively, whereas co-knockdown of ASCT2 and SPOP also caused growth suppression (Fig. 6f, g, Supplementary Fig. 8a, b), suggesting that while SPOP acts as a growth suppressor, ASCT2 plays the major role for the growth and survival of breast cancer cells. Here, SLC1A5 is linked to breast cancer.