Because of its importance in glutamine metabolism, there have been considerable efforts to target ASCT2 in cancer.47,60,73 Current ASCT2 inhibitors include the pseudo-metabolites benzylserine74 and GPNA (L-γ-glutamyl-p-nitroanilide)75 as well as the small molecule V-9302.76 While benzylserine and GPNA can reduce breast cancer cell growth by inhibiting uptake of several amino acids,74 they will likely not be useful clinically due to the high millimolar concentrations required to be effective. This evidence concerns the gene SLC1A5 and breast cancer.