Co-expression map of 23k genes over 24 cell types of the B-cell family. The top view illustrates how maps are combined with client-side graphics: the map is at the center of the display while selecting genes on the map generates the heatmap on the right. Maps have multiple levels of zooming (bottom row), each with a potentially different representation. For example, genes are drawn as heatmap glyphs at the high zoom (lower right), and as dots at low zoom. Expression profiles of collocated genes are aggregated and displayed as yellow glyphs over the map. As zoom increases, expression profiles are computed for increasingly smaller regions. Interactions are not limited to zooming and panning; pop-up boxes link out to further data sources and selections of genes bring up a heat map (top panel).