Kristiansen et al. BMC Genomics 2011, 12:551 http://www.biomedcentral.com/1471-2164/12/551 Page 7 of 17 Figure 4 Top 50 genes up- and down-regulated in sympathetic neurons after NGF withdrawal. Heatmaps showing the expression of the 50 genes most significantly up- and down-regulated in sympathetic neurons after NGF withdrawal compared to other treatments as indicated. Cluster analysis was performed on the genes and the treatment groups according to their expression profiles and the corresponding dendrogram is shown to the left and to the top of the heatmap respectively. Treatment groups are colour coded as follows: blue, sympathetic neurons cultured in the presence of NGF for 16 hours (+NGF); pink, sympathetic neurons cultured in the absence of NGF and in the presence of an anti-NGF antibody (-NGF); yellow, sympathetic neurons cultured in the absence of NGF and in the presence of an anti-NGF antibody and the compound CEP-11004 (+CEP). A green-red colour palette illustrates the log2 gene expression values, with green corresponding to low and red corresponding to high expression. The numbered arrows refer to the 4 major patterns of expression as described in the results. *Genes with unknown annotation.