An enhancer element in the ANK1E DNase I–sensitive chromatin domain. Overlapping fragments of the ∼ 11 kb region (shown below with the locations of 5′HS, 3′HS1, and 3′HS2) were cloned into an ANK1/luciferase vector and transfected into K562 cells. The bar graph shows the relative luciferase expression of each fragment compared with the ANK1E promoter alone. The black bars indicate fragments with significantly higher levels of luciferase expression (*P < .01). Mutation of the NF-E2 (Δ) or NF-E2/AP1 (ΔΔ) binding sites abolishes the activity of 3′HS1 (+, P < .01; compared with wild-type fragment 11).