Activity of multimers of the CCACCC and CCAAT box regions of the γ-globin promoter. A trimer of the CCACCC box region (−148/−135) or a dimer of the CCAAT box region (−126/−66) was cloned into the −54 γ-globin promoter-CAT plasmid. These constructs were then transfected into K562 cells that were left untreated (▪) or treated with 1 mmol/L arginine butyrate (). A representative experiment of three trials for each multimer is shown.