Cis-elements within –5.5HSCR are specifically occupied in endothelial cells. (A) Analysis of both DNA strands of the –5.5HSCR sequence by in vivo DMS footprinting. DMS methylation of naked genomic DNA (G) is compared with in vivo methylation of HepG2 (H) and HUVEC (E) DNA. Open circles represent at least 2-fold protection, and closed circles represent at least 2-fold enhancement of DMS reactivity of E relative to H and G. Potential transcription factor binding sites corresponding to the footprinted regions are indicated at the right of each gel image. (B) DNA sequence of both strands of –5.5HS (from –5835 to –5283 bp relative to the hEPCR ATG start codon) encompassing –5.5HSCR (bold). Guanines specifically footprinted in ECs are denoted by circles. Putative binding sites for 2 Ets (nos. 1-2), a GATA, and a Tal1 transcription factor are boxed and labeled. (C) Alignment of upper DNA strand of –5.5HSCR with its murine counterpart (located –8.3 kb relative to mEPCR).