To confirm that the observed hypoxia-dependent changes in the expression pattern of these acid/base-regulatory proteins are not specific to the MCF-7 cell line, we also determined the expression levels of MCT1, MCT4, NHE1, NBCn1, CAII, and CAIX in the triple negative breast cancer cell line MDA-MB-231. The gene discussed is CA9; the disease is triple-negative breast carcinoma.