UniProt Summary: Sodium-independent, high affinity transport of large neutral amino acids. Has narrower substrate selectivity compared to SLC7A5 and SLC7A8 and mainly transports branched-chain amino acids and phenylalanine. Plays a role in the development of human prostate cancer, from prostatic intraepithelial neoplasia to invasive prostate cancer. {ECO:0000269|PubMed:11956097, ECO:0000269|PubMed:12930836, ECO:0000269|PubMed:9255310, ECO:0000269|PubMed:9722952}.