The SET1 complex is required for maintaining H3K4 methylation and recruitment of the NURF complex at the endogenous 5′HS4 insulator of the chicken β-globin locus. (A) Schematic representation of the chicken β-globin cluster. Open arrows indicate locations of primer sets used in ChIP analysis. (B-C) Histone-modification patterns at the 5′HS4 insulator element are disrupted in SET1-depleted cells. ChIP analysis of H3K4me2 (B) and H3K9K14ac (C) at the endogenous 5′HS4 region in wild-type (white bars) or SET1 KD (black bars) cells. Relative enrichments were normalized to those observed at the HSA element to adjust for immunoprecipitation efficiency. (D) ChIP analysis of dimethyl H3K9 at the 5′HS4 insulator element. (E) ChIP analysis of BPTF at the 5′HS4 insulator element in 6C2 cells harboring the vector control and shSET1. *P < .01 by Student t test. Shown are the means ± SEM of 3 independent experiments.