Universe of promoters that possess each epigenetic mark. A. Examples of each epigenetic mark for a single promoter from each BTSC type. Note great similarity in waveforms across cell types for a given epigenetic mark. Left axis is log2 enrichment ratio. For genomic location (top axis), only single coordinate is shown; genomic distance between tick marks is (panels from left to right): 1 kb, 6 kb, 4 kb, 8 kb. All displayed transcripts extend beyond edge of figure area. B. Diagram of number of promoters that possess a given epigenetic mark in at least one type of BTSC (“universe” set; number in parentheses) and the number that possess it in every BTSC type (“core” set). Number in core set: H3K4me3: 6742; H3K9me3: 1650; H3K27me3: 3198; meC: 5360. See RESULTS and METHODS for details of computation of sets.