Electroneutral K⁺/Cl⁻ cotransporter 4 (SLC12A7) localized to the basolateral membrane of alpha-intercalated cells in the renal collecting duct and supporting cells of the organ of Corti in the inner ear. Facilitates coupled basolateral Cl⁻ extrusion necessary for transepithelial proton secretion (systemic acid-base homeostasis) and endolymphatic potassium recycling. Overexpressed in invasive cervical and ovarian carcinomas, promoting tumor cell motility and metastatic invasion.