RAR binding sites are coincident with ES cell transcription factor binding and H3K4 methylation. (a) Percentages of binding sites within 200 bp of ES cell binding events. Coincidence rates between 10,000 random genomic locations and ES cell binding events are shown for reference. In cases where the same protein was profiled by multiple labs, we denote the source using the following abbreviations: B, Bernstein lab [38–40]; N, Ng lab ; Y, Young lab . (b) Rates of post-ES cell binding sites where at least one ES cell TF binding site (of 13 profiled TFs) is within 200 bp. HSC, hematopoietic stem cell.