Because NaV1.5 was demonstrated to promote breast cancer cell invasiveness through a promotion of extracellular acidification involving NHE1 allosteric activation49,50, we monitored the H+ efflux at the introduction of NaCl in MDA-MB-231 cells previously acidified (NH4Cl pulse-wash protocol in sodium-free medium). The gene discussed is SLC9A1; the disease is breast carcinoma.