Among the cationic amino acid transporter/glycoprotein-associated family, SLC7A5, SLC7A7, and SLC7A8 are highly expressed in luminal subtypes of breast cancer, as well as SLC7A9 and SLC7A10, the activity of which is observed exclusively in the case of positive HER2 expression. The gene discussed is SLC7A8; the disease is breast cancer.