The Expression Atlas is an added-value database based on re-analysis of (RNA-seq and microarray) gene and protein expression data from EMBL-EBI's ArrayExpress and PRIDE archives respectively, as well as from external sources. It shows you which genes/proteins are expressed under different conditions (e.g. tissues, cell types, cell lines, strains or developmental stages), and how expression differs between conditions (e.g. comparing disease to healthy). Future development will include metabolite expression data.