Methylation of CpGs sites in MGMT promoter, one of the major post-transcriptional mechanisms reducing MGMT protein expression, has been found in 40 % of cancer such as glioma and colorectal cancer and in 25 % of non-small cell lung carcinoma, lymphoma, and head and neck carcinoma [33, 34]. The gene discussed is MGMT; the disease is colorectal cancer.