To investigate the effects of DNA demethylation on chromatin architecture and gene expression, we treated the RKO colon cancer cell line, with 1 uM 5-Aza-CdR for 24 hours and followed the sequential changes in mRNA expression, DNA methylation and histone marks at the promoters of the MLH1, CDKN2A and MYOD1, which are methylated and silenced in RKO cells (Figure 1). The gene discussed is MLH1; the disease is malignant colon neoplasm.