CA9 and neoplasm: To identify potential CAIX-associating partners and investigate the mechanism of CAIX-mediated tumor cell invasion, we utilized a global, unbiased proteomic approach using a BioID analysis,28 a highly robust technique for mapping highly complex protein interactomes.44 The CAIX interactome that we identified reveals that CAIX associates with several metabolic cell surface transporters which may be critical for the metabolic response to hypoxia.