It is especially noticeable that the protein expression levels of NBCn1 and NHE1 (Figures 5E,F and 6E,F) are elevated in breast cancer tissue with HER2 overexpression or gene amplification despite low SLC4A7 and intermediate SLC9A1 mRNA levels (Figures 9A and 10A). Here, ERBB2 is linked to breast cancer.