ODC1 and malignant colon neoplasm: A previous study has shown that the transcriptional repressor Mad1 suppresses the activity of the ODC1 promoter in colon cancer cells containing the A-allele but not the G-allele, and other studies have also reported that the E-box repressors MAD4 (MXD4) and MXI1 bind less strongly in cells homozygous for the GG genotype [18,19].