To investigate whether interference with the CAIX PG domain can also inhibit the hypoxia-induced augmentation of proton-coupled lactate transport in cancer cells, we incubated MCF-7 (Figure 5) and MDA-MB-231 (Figure 6) breast cancer cells under normoxia (20% O2) or hypoxia (1% O2) in the presence of 5 μg/ml Anti-PG, 5 μg/ml Anti-CA, or without antibodies (Ctrl). The gene discussed is CA9; the disease is cancer.