Figure 4

MAL expression in cancer cell lines and colorectal carcinomas. Promoter hypermethylation of MAL was associated with reduced or lost gene expression in in vitro models. The quantitative gene expression level of MAL is displayed as a ratio between the average of two MAL assays (detecting various splice variants) and the average of the two endogenous controls, GUSB and ACTB. The value has been multiplied by a factor of 1000. Below each sample the respective methylation status is shown, as assessed by methylation-specific polymerase chain reaction. Filled circles represent promoter hypermethylation of MAL, open circles represent unmethylated MAL, and open circles with a slash represent the presence of both unmethylated and methylated alleles. Colorectal carcinomas are divided in an unmethylated group (n = 3) and a hypermethylated group (n = 13), and the median expression is displayed here. The tissue of origin for the individual cell lines can be found in table 1.