SLC3A2 and triple-negative breast carcinoma: When comparing the levels of SLC3A2 CN and mRNA expression in the intrinsic (PAM50) subtype,30 high mRNA expression was observed in basal-like, luminal B and HER2+ tumours (Fig. 2e, p < 0.001), whereas SLC3A2 CN gain was primarily observed in luminal B subtype and to lesser extent in HER2+ and triple negative breast cancer  (TNBC) (p < 0.001, Supplementary Table 3).