MGMT and cancer: Despite an overall reduction of DNA methylation (global hypomethylation), hypermethylation of CpG islands of tumor suppressor gene promoters was found in almost all cancers, which lead to transcriptional silencing and result in tumorigenesis, such as those involved in cell cycle regulation (APC, p16 INK4a, p14ARF), DNA repair (BRCA1, MGMT), apoptosis (RASSF1A, DAPK, TMS1) [1].