Domain formation after inhibition of RNA Pol II elongation by DRB. (A) DRB effect on mature and primary mRNA transcripts of the embryonic βh1 globin gene. (B) ChIP results for RNA Pol II at the promoters and the 3′ region of ϵy and βh1 in untreated (■) and DRB-treated () samples. (C) H3Ac (top) and H3K4 dimethyl (bottom) ChIP results for E12.5 peripheral blood across the region harboring the embryonic β-globin genes in untreated (□) and DRB-treated (■) cells.