Fig. 1

Aligning annotated transcription units with genomic data. Genome browser tracks of various types of genomic data (GRO-seq; polyA+ RNA-seq; Pol II, H3K4me3, and H3K36me3 ChIP-seq) from MCF-7 cells, an estrogen receptor alpha (ERα)-positive human breast cancer cell line. GRO-seq and Pol II ChIP-seq mark the entire transcription unit of actively transcribed genes (“Expressed”). PolyA+ RNA-seq marks exons, 5′ UTRs, and 3′ UTRs of actively transcribed genes. H3K4me3 and H3K36me3 mark the promoters and gene bodies, respectively, of actively transcribed genes. Transcription units called by groHMM using GRO-seq data are shown in comparisons to RefSeq annotations