We have, however, recently demonstrated that at least under some conditions, including in vitro models of HER2 positive breast cancer, and measurements obtained directly in freshly dissected human mammary carcinomas, bicarbonate transporters such as the electroneutral Na+, HCO−3 cotransporter (SLC4A7, NBCn1), are upregulated and play central roles in pH regulation. This evidence concerns the gene ERBB2 and breast carcinoma.