GAPDH and colorectal carcinoma: The gene expression level of EDNRB was normalized with the values of the control gene GAPDH. Our results showed that EDNRB mRNA level in CRC tumor samples was significantly lower than in their adjacent normal samples (0.31 ± 0.91 versus 0.70 ± 1.18, p = 0.032, Figure 3, Table 4).