(A) Schematic representation of the region of HS3 analyzed in this study. Stippled rectangles indicate two regions of DNaseI hypersensitivity. The darker, longer rectangle is the region referred to as the “core” of HS3 while the other, more 5′ rectangle represents a second hypersensitive region.22 The 24 phylogenetic footprints (FP1-24) are indicated as numbered black vertical bars. Beneath the footprints, the relative locations of the probes used for gel shift analysis is shown, and the position of the 5′ end of each probe with respect to the HUMHBB (GenBank) sequence is indicated. The positions of several landmark restriction sites are shown below the probes, and the regions of HS3 that have been used in functional assays are indicated. The end-points of deletions of HS3 tested in functional studies are also shown.52 53 (B) Probe overlaps are documented schematically; the length of overlap is given in base pairs. Here, as in the text, probes are referred to by the footprint number rather than the position in the sequence.