CA9 and melanoma: These observations are particularly intriguing given that previous studies using exogenously expressed MMP14 as bait in a melanoma cell line identified 158 potential proteins that associate with MMP14, including membrane proteins such as integrins, although these associations were not validated by co-IP.45 CAIX was not identified as an associating partner of MMP14 in this study, a result that is not surprising given that the experiments were performed only in normoxia, precluding expression and association of hypoxia-induced proteins.45