Decreased level of circulating amino acids is linked to increased uptake by cancer cells due to overexpression of amino acid transporters, including SLC1A5 (Gln uptake), SLC1A4 (Ser uptake), SLC7A5 (Leu, Ile, and Val uptake), or SLC7A1 (Arg uptake) (4). Here, SLC7A5 is linked to cancer.