The FANTOM5 consortium aimed to generate both a map of the majority of human promoters and comparative transcriptional regulatory network models of each cellular state. To achieve this they carried out CAGE sequencing on the Heliscope true single molecule sequencer on RNA isolated from every major human organ, over 200 cancer cell lines, 30 time courses of cellular differentiation, mouse developmental time courses and over 200 primary cell types. The result is a unique body-wide atlas focused specifically on core promoter utilization. CAGE tags mapping to the reference genome were clustered to tag clusters, corresponding to regions of transcription initiation. For simplicity, we will refer to these regions as “promoters”. Within each such region, we have a measure of expression within each primary cell and tissue and based on the expression levels, an promoter can be specific to a set of primary cells and organs (tissue samples) or can be broadly (or ubiquitously) expressed. In SlideBase, each such promoter with associated expression data is the unit that can be searched for.