Histone modifications across the β-globin locus during ES cell differentiation. The murine β-globin locus and locations of amplimers used for quantitative PCR are shown at the top, as in Figure 1. (A) Enrichments for H4Ac and H3K4 dimethyl within the β-globin locus in undifferentiated ES cells. (B) Globin mRNA expression during days 2 to 8 of EB differentiation, normalized to 18s mRNA. (C) Benzidine staining during days 2 to 8 of EB differentiation. (D) Enrichments for H4Ac (top) and H3K4 dimethyl (bottom) in EBs differentiated for 2, 4, 6, and 8 days.