Narrowing down existing gene signature to few genes. 23 human medulloblastoma expression profiles implemented by Affymetrix G110 cancer arrays were used . Among them, 10 were metastatic tumours and 13 were non-metastatic tumours. This plot illustrates how users can filtrate out a handful of genes for diagnostic purpose by applying SET. The left panel is the heat map of the original signature , and arrows indicate mis-grouped samples. The middle panel shows two figures produced by SET (see Figure 2 for more details). The right panel is the heat map of the filtrated 4 new diagnostic markers.