SPOP and breast cancer: It is noteworthy that in breast cancer cells, (1) neither ASCT2 nor SPOP is subjected to glucose regulation, since glucose deprivation has no effect on their protein levels (Supplementary Fig. 5b, c); (2) glutamine deprivation has no effect on the levels of neddylation activating enzyme (NAE) E1 (including both subunits, NAE1/AAPBP1 and UBA3/NAEβ), and two E2 neddylation conjugating enzymes (UBE2M and UBE2F) (Supplementary Fig. 5h, i).