Figure 4.

Inhibition of transcriptional activation by placement of the 5.1-kb phage DNA fragment between HS2 and the promoter. (A) Structure of test constructs. (B) Test and selection constructs were linearized and cotransfected into K562 cells. Stably transfected pools of cells were isolated and assayed for luciferase activity as a measure of γ-globin promoter activity (mean ± SEM, n = 11, 9, and 9, and 9 for constructs 1–4, respectively).