β-Like globin gene expression after in vitro erythroid differentiation of 5′HS2 mutant ES clones. Sample gels are shown. S indicates the single allele, and D, the diffuse allele on which mutations are made; ΔHS2c, the core deletion; and ΔHS2full, the full site deletion. Wild-type (WT) values are the WT D/S ratio normalized to 1.0. The mutant/S ratio is divided by WT D/S ratio before normalization of WT D/S. Error bars represent the standard deviation of the mean for 10 individual primitive (Bh1 assay) or definitive (Bmajor and Bminor assay) erythroid colonies before normalization.