SLC9A1 and triple-negative breast carcinoma: Most importantly, a series of publications in this line have shown that the H+ extrusion in BC cells, especially in triple-negative breast cancer (TNBC), is mainly mediated by NHE1 overexpression and H+-extrusion, with NHE1 being the real actor that induces a high pHi-mediated carcinogenic effect on breast cells [44].