The relationship between subpopulations in origin-related samples. Twenty-nine pairs of breast primary tumors (T), lymph node metastases (M) and four "normal" breast tissue samples (N) were analyzed by unsupervised clustering. The similarity of genomic profiles of subpopulations between samples is displayed by clustering (right). The corresponding hypothetical models are shown in the left. The subpopulations presenting the same color denotes they have a close relationship. For more explanations see the text.