MLH1 and colorectal carcinoma: The MSI+ CRC cell line CO-115 (heterozygous for rs1800734 (A/G), BRAFV600E) has very high levels of methylation at all CpGs analysed in the MLH1 promoter (Fig. 3a, mean = 91%) and expression of MLH1 is undetectable by Q-PCR (Fig. 3b).