Range of biological variability of the gene expression dataset. Similarity dendrograms (Pearson correlation) resulting from hierarchical clustering of tumor samples from CRC patients based on the global gene expression matrix. Letters refer to the origin of the biopsies, colon tumors (T), liver metastases (M) or adjacent non-tumoral colons (N). Numbers refer to individual patients. For each sample, the color patch represents the primary drug response rate, either resistant (in red) or sensitive (in blue), subsequently diagnosed in patients at the presentation of the drugs. Color squares around the gene expression matrix display specific subgroups of clusters. The yellow square shows the cluster of N samples, while the gray one refers to the clusters of cancerous samples (T&M); red and blue squares specify predictive (resistant and sensitive) subgroups of cancerous samples.