HDAC inhibitors induce γ -globin gene expression in human BFUe cultures. Cultures done in the presence of 8 compounds that induced the γ globin gene promoter in the dual luciferase assay. • indicates levels of γ mRNA (expressed at percentage of γ/γ + β ratios). ○ indicates frequencies of HbF-positive erythroblasts. The data represent means ± SEMs derived from 3 to 5 independent BFUe cultures done with mononuclear cells of different adult individuals. Notice that both the level of γ mRNA and the frequency of F-positive erythroblasts increase in response to these compounds.