CAIX is a CA isoform overexpressed in hypoxic conditions and constitutively expressed in the majority of cases of the most common type of RCC, the ccRCC, due to mutations of the VHL gene, CAIX is being used as a ccRCC biomarker and has been shown to have prognostic implications [82, 83]. Here, CA9 is linked to nonpapillary renal cell carcinoma.