Patterns of histone acetylation at the promoters of the β-like globin genes in erythroid (K562 and BFU-E) and nonerythroid (HeLa and CFU-GM) cells. (A) Schematic map of the human β-globin gene cluster in which the 5 genes are represented by solid boxes. The regions analyzed for histone acetylation are marked by a horizontal line under the map. (B,C) Levels of acetylation of histones H3 (acH3) and H4 (acH4) and their sum (acH3 + acH4) at the promoters of ϵ-, γ-, and β-globin and α-actin genes assessed by quantitative real-time PCR-based ChIP analysis. The data are expressed in relative units. Error bars are SD. This experiment is representative of 3 independent experiments.