Notably we did not see a significant difference in transporter gene expression in MDA-MB-231 cells (Fig. 4b) or claudin-low tumours from the METABRIC cohort (Fig. 4c-h), indicating that expression levels do not necessarily correlate with the importance of a transporter, as we have shown previously for ASCT2 [15]. This evidence concerns the gene SLC1A5 and neoplasm.