The GEPIA database was next utilized to compare the expression of different CLDN family members in CRC and in normal colon tissue samples, revealing CLDN1, CLDN2, CLDN3, CLDN4, CLDN7, and CLDN12 to have been upregulated and CLDN5 and CLDN11 to have been downregulated in COAD and READ tissues relative to control samples (Figure 2). Here, CLDN4 is linked to colorectal carcinoma.