CA9 and breast cancer: Meehan and colleagues showed that breast cancer cell lines MDA-MB-231, MCF-7 and HBL-100 are expressing CAIX, NHE1 and V-ATPase and treatment with S4 (CAIX inhibitor), DMA (NHE1 inhibitor) or bafilomycin A1 (V-ATPase inhibitor) reduced proliferation.