A map of the 35-kb region of genomic DNA in and upstream of the human ABO gene. The top diagram indicates the ABO gene exons 1-7 as represented by vertical lines with coordinates in hg18. The second diagram from the top indicates DHSs that were constructed through Washington digital DNase genomic footprinting on the UCSC genome browser. DHSs are denoted by arrows and contiguous DHSs are integrated into one site and represented by a thick arrow. These DHSs are referred to as −8.8, −5.5, −3.8, −0.7, −0.1, +2.0, +5.8, and +11.5. The third diagram from the top indicates the locations of DNA fragments that were obtained by PCR amplification or restriction enzyme digestion of human genomic clone HG-1, followed by subcloning upstream of the ABO proximal promoter in reporter plasmids. The solid boxes represent PCR amplicons and the clear boxes indicate the genomic DNA fragments from the HG-1 clone. Transient transfection into K562 cells was performed using 2.5 μg of firefly luciferase reporter plasmid and 0.01 μg of pRL-SV40 Renilla luciferase reporter vector for each analysis. The diagram at the bottom shows the activities of individual reporter plasmids, in which the activity of reporter plasmid SN containing the promoter was assigned an arbitrary value of 1.0, indicated by a clear box. The results are expressed as an average of the relative activity observed. The mean values were calculated from more than 3 independent experiments. DNA regions −8.8, +5.8, and +11.5 were inserted upstream of the promoter sequence in both directions, and luciferase activity is expressed as the average activity of reporter plasmids in which the same DNA fragment was inserted in either direction.