CDX1 and colorectal cancer: In the same rules for identifying colon tissues, Gpx2, which encodes the protein of the glutathione peroxidase family, requires a high expression like that of Cdx1. This gene is predominantly expressed in the gastrointestinal tract, and the overexpression of Gpx2 is associated with increased differentiation and proliferation in colorectal cancer (Komatsu et al., 2001), thus contributing to colon development.