Comparison of standard SOM in log FC-scale (panel a) with rank maps based on global gene lists according to the t-shrinkage statistics (panel b). Metagenes of high overexpression and of small average rank of the associated single genes are coded in red. Both options show essentially similar textures. The rank maps partly reveal more detailed spot pattern or a low overall rank level (blue, e.g. colon). The atlas of rank maps of all tissues studied is shown in Additional file 2.