Figure 4.

A cellular mechanism of field change. In carcinogen exposed tissues mutations in genes such as p53 (red) are frequent. However, stochastic differentiation leads to most such mutant clones being shed from the epithelium (marked X). However, if a p53 mutant cell is subject to a Notch inhibiting mutation, it achieves clonal dominance. Over time the double mutant clone expands to colonize a large area, resulting in a region of epithelium at increased risk of malignant transformation as it acquires further mutations.