Definition of top-level clusters. Top-level clusters (top) were obtained by overlapping defined core promoter regions (-300, +100 bp) of CTSSs. If core-promoters of CTSSs overlap, they are clustered together. Blue regions denote core promoter regions for each CTSS (red bars).
Akalin et al. Genome Biology 2009 10:R38 doi:10.1186/gb-2009-10-4-r38