Using an engineered metastatic niche, we identified a 9‐gene signature (Dhx9, Dusp12, Fhl1, Ifitm1, Ndufs1, Pja2, Slc1a3, Soga1, Spon2) that successfully delineated metastatic breast cancer from nonmetastatic breast cancers including an invasive cell line without metastatic potential. This evidence concerns the gene SLC1A3 and breast cancer.