MLH1 and colorectal carcinoma: Previous studies proposed a subdivision of the CpG island from four to five regions [12,13,14,15,16] to cover most CG dinucleotides, and only Deng et al. (1999, 2001) [15,16] found a relationship between the methylation status of four regions of the CpG island and the inhibition of MLH1 expression in CRC cell lines.