Although not normally expressed at high levels in breast tissue, we and others have reported that breast cancers [14, 23–25] and breast cancer cell lines [15, 26, 27] express high levels of the known BenSer targets, LAT1 and ASCT2, but little is known about the expression of these other novel BenSer targets in breast cancer [28–32]. The gene discussed is SLC1A5; the disease is breast cancer.