Interestingly, NHE1 not only co-precipitated with CAIX but also with the Na+/Ca2+ exchanger NCX1, which is closely colocalized to CAIX and NHE1 in hypoxic SiHa cells and RCC4 renal cell carcinoma cells, respectively. This evidence concerns the gene SLC9A1 and hereditary clear cell renal cell carcinoma.