SLC1A5 and cancer: Uptake of 18F-FGln, a glutamine analog that is used for PET imaging of cancer (22–26) correlates with upregulation of alanine-serine-cysteine transporter 2 (ASCT2), a sodium-dependent neutral amino acid transporter of glutamine (27); as such, it detects lesions more sensitively than 18F-FDG (23).