Up-regulation of MAL expression after drug treatment. Decreased promoter methylation of MAL followed by up-regulated mRNA expression in colon cancer cell lines was found after treatment with the demethylating 5-aza-2'deoxycytidine, alone and in combination with the deacetylase inhibitor trichostatin A. Upper panel demonstrate the relative expression values of MAL (linear scale) in two colon cancer cell lines, HT29 and HCT15, treated with 5-aza-2'deoxycytidine alone, trichostatin A alone, and the two drugs in combination. Lower panel illustrate MAL MSP results for the same samples. A visible PCR product in lanes U indicates the presence of unmethylated alleles whereas a PCR product in lanes M indicates the presence of methylated alleles. Abbreviation: AZA, 5-aza-2'deoxycytidine; TSA, trichostatin A; Pos, positive control (unmethylated reaction: DNA from normal blood, methylated reaction: in vitro methylated DNA); Neg, negative control (containing water as template); U, lane for unmethylated MSP product; M, lane for methylated MSP product.