Transfection of the tumor-associated isoform of CA IX into Madin-Darby Canine Kidney (MDCK) epithelial cells showed lower extracellular pH than did mock-transfected cells 48 h after incubation in hypoxia, in contrast to normoxia, which produced no significant difference in either group (Svastova et al., 2004). Here, CA9 is linked to neoplasm.