The Immunological Genome (ImmGen) Project provides gene expression data for various immune cell types in the mouse. These data are now available in iPad/iPhone format with the free ImmGen app. On the homescreen, users search for a gene of interest to display the expression data for that gene in seven immune cell types—B cells, γδ T cells, αβ T cells, activated T cells, NK cells, myeloid cells, and stromal cells—as well as immune precursor cells. The expression data are displayed in heat-map form for each cell type, with each box corresponding to a specific experiment. Users can select a specific cell type to bring up those data fullscreen, as a bar chart. While brief summaries of each experiment (i.e. cell sample and number of replicates) can be displayed, it is unfortunate that citations are not also provided so that users can get more detailed information about the experiments.