Two other sodium-independent large amino acid transporters, SLC43A1 and SLC43A2 are also absent, leaving SLC6A15 encoding a known transporter of BCAA found in the mammalian brain, and SLC7A6, an antiporter exporting Arg and Lys in exchange for Leu, Ile and Gln also expressed in brain and cancers. Here, SLC7A6 is linked to cancer.