“Cancer arises from the stepwise accumulation of genetic changes that confer upon an incipient neoplastic cell the properties of unlimited, self-sufficient growth and resistance to normal homeostatic regulatory mechanisms. Advances in human genetics and molecular and cellular biology have identified a collection of cell phenotypes — the main destinations in the subway map — that are required for malignant transformation. Specific molecular pathways (subway lines) are responsible for programming these behaviours.” (William C. Hahn and Robert A. Weinberg – Nature)