Patterns of DNA methylation at the promoters of the γ- and β-globin genes in erythroid (K562 and BFU-E) and nonerythroid (HeLa and CFU-GM) cells. (A) Example of pyrograms generated from pyrosequencing reactions at CpG sites −54 and −51 of the γ-globin promoters (shadowed area). (B,C) Levels of DNA methylation at 5 CpG dinucleotides at γ-globin promoters and 3 CpG dinucleotides at the β-globin promoter were determined by pyrosequencing. The data are expressed as percent methylation. Error bars represent SD. This experiment is representative of 3 independent experiments. T indicates thymidine; C, cytosine.