ATF4 regulates BCL11A through the +55 enhancer. (A) BCL11A mRNA (top) and γ-globin mRNA (bottom) levels measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR) relative to AHSP mRNA in BCL11A +55 sgRNA-treated and control HUDEP2 cells. Results are shown as mean ± standard deviation (SD; n = 3). (B) BCL11A mRNA (top) and γ-globin mRNA (bottom) levels measured by RT-qPCR relative to AHSP mRNA in BCL11A +55 sgRNA-treated and control primary erythroid cells. An sgRNA against the +58 enhancer served as positive control. Results are shown as mean ± SD (n = 3). (C) Representative high-performance liquid chromatography (HPLC) analysis of Hb in primary erythroid cells. HbF peaks are indicated by red arrows, and HbF peak area is displayed as percentage of total HbF + HbA. (D) Capture-C using the BCL11A promoter as anchor. The erythroid specific enhancers +55, +58, and +62 are highlighted in purple, and the BCL11A promoter anchor in cyan. The segment used for quantification of reads is indicated by the blue bar (supplemental Figure 4G). H3K27ac and DNaseI were obtained from published data.41 *P < .05, **P < .01 by Student t test. WT, wild type.