Figure 2: Genes differentially expressed after induction of apoptosis in CGNs. To induce apoptosis, cultures were switched in serum-free medium containing 5 mM KCl in the absence (-KS) or presence of 10 μM Actinomycin D (-KS + ActD). Control cells (control) were maintained in complete medium. 421 genes showed significant changes of gene expression following induction of apoptosis at 3 h and/or 6 h [7]. A hierarchical clustering algorithm (similarity measure: euclidean; linkage rule: complete) was used to order these genes in a dendrogram, in which the pattern and length of the branches reflects the relatedness of the expression levels in different experimental conditions. Data are presented in a matrix format: each row represents a single gene and each column an experimental condition. The averaged normalized intensity from replicates is represented by the color of the corresponding cell in the matrix. Blue, white and red cells, respectively, represent transcript levels below, equal or above the median abundance across all conditions. Color intensity reflects the magnitude of the deviation from the median (see scale at the bottom).