AQP8 and colorectal carcinoma: We then examined 3 genes (polycythemia rubra vera protein 1 (CD177), aquaporin 8 (AQP8) [25] and glutathione peroxidase 3 (GPX3)) whose expression is characteristic of normal enterocytes and which are downregulated in CRC as shown in meta-analyses of microarray and immunochemistry studies [5, 6].