Researchers at The Roslin Institute have characterised the global expression pattern of all the known pig genes by measuring their mRNA levels across a wide range tissue and cell types. Image The DNA sequences available for all pig genes were used to design a new Affymetrix gene expression microarray which provides comprehensive coverage of the pig transcriptome; the transcriptome is the set of all RNA molecules produced by the cells of an organism. This microarray was used to assay the transcript levels for thousands of genes across 62 different samples of pig tissues/cells. These data have allowed for the construction of the first atlas of gene expression for the pig where the function of a gene can be inferred from its pattern of expression and other genes expressed in a similar pattern. The results are published in BMC Biology (www.biomedcentral.com/1741-7007/10/90) as one of the companion papers (www.biomedcentral.com/series/swine) associated with the pig genome sequence paper. The data and analyses are available on the BioGPS Gene Portal web site at biogps.org which provides a user friendly view of the expression profile for each gene. The data and analyses are also available on the Macrophages.com site at www.macrophages.com/pig-atlas. Downloadable Files BMC Biology Companion PaperBMC Biology 2012, 10:90