SET1 and NURF complexes interact with the 5′HS4 insulator in vivo. ChIP analysis in chicken erythroid progenitor 6C2 cells. (A) Schematic representation of the chicken β-globin cluster is shown. Open arrows indicate locations of primer sets used in ChIP analysis. ChIP analysis of SET1 (B), BPTF (C), and SNF2L (D) compared with IgG. Comparison of hSET1 enrichments at the human β-globin HS2 and the negative control region 3′HS, as well as at the chicken β-globin locus HSA and HS4 and the negative control region 16 kb and 3′HS (B). *P < .01 by Student t test. Shown are the means ± SEM of 3 independent experiments.