Subgroups of different cancers can be identified using a proneural signature. Expression vectors of neuroendocrine biomarkers across the 1786 sample ExpO data set are shown in the heatmap. This was generated using the heatmap function within Bioconductor. Each gene is scaled to its median intensity across all samples. Samples displaying a greater than 3 fold increase in expression for each of the neuroendocrine gene sets are highlighted with black bars above the heatmap. These samples were tested for enrichment of malignant tissue types (Table 3). Malignant tissue samples enriching proneural signature sample groups are highlighted as coloured bars at the top of the heatmap.