Table 2.

Summary of the contents of the mapper₂ database, by organism

	Human	Mouse	Drosophila
Models	832	829	819
Genes	21 510	21 736	14 003
Promoters	34 022	27 443	22 369
Total bases (Mb)	628	578.6	266
Total hits	33 122 746	24 313 246	19 248 318
Hits/promoter	973.5	886.0	860.5
Hits/model	1.17	1.06	1.05
Hits spacing	18.95	23.80	(13.82)

‘Models’ indicates the number of models that produced at least one hit in a genome. ‘Hits/model’ represents the average number of hits in a promoter for each model. ‘Hits spacing’ is the average number of nucleotides between hits (see text for an explanation of the Drosophila value).