CTCF binding is highly conserved across primates. (A) Categorization of CTCF binding events on the basis of their evolutionary conservation. Fraction of all CTCF-bound regions across species that are not contained within the EPO multiple alignments (−), present in a single species (1) and shared among two, three to five, six, or all seven primate species. (B) The fraction of primate-shared CTCF binding events (LCL) found in mouse (liver). (C) The fraction of CTCF binding events in each species overlapping human CTCF binding events. Species are ordered by evolutionary divergence time (millions of years). H.sap, P.tro, G.gor, P.pyg, M.mul, P.ham, S.oed LCL CTCF binding data (blue); H.sap M.mul and M.mus liver CTCF binding data  (grey). The human fraction is based on inter-individual overlaps. (D) Regions bound in four macaque cell lines (left) or one macaque cell line (right) have different patterns of conservation between species (colored as in panel A).