Effect of DAC on rRNA expression and rDNA promoter methylation in myeloid leukemia cell lines. (A-C) THP1, Mono Mac 6, and ML2 cells were treated with DMSO or 0.1μM DAC for 3 days. The level of expression of pre-rRNA is shown relative to that in DMSO-treated cells. GAPDH was used as an internal control and the samples were run in triplicate. (D-F) The cells were treated with DMSO or 0.1μM DAC for 3 days and the extent of CpG methylation was determined by pyrosequencing at CpGs 7-23 spanning the rDNA upstream core element and the core promoter.