Figure 2.

A simplified graphical depiction of 2 competing hypotheses regarding whether cell-to-cell communication is part of the fitness landscape. The left panel represents a null hypothesis that cell-to-cell communication is not a component of the fitness landscape and that malignant clones diverge from the origin in a way that is consistent with standard evolutionary theory. The right panel represents an alternative hypothesis that cell-to-cell communication is a component of the fitness landscape and that this communication must be altered in a particular way for malignant cells to dominate this tissue niche. The secretome of a normal cell is represented by the red dot at the center of the 2 panels. The dotted and solid red lines depict the evolutionary paths associated with oncogenesis of 2 malignant clones that arise within the same anatomical niche. The extent of the selective pressure exerted on a cell is depicted using black-white shading, where white indicates no selective pressure and black indicates high selective pressure.