Understanding how the field effect arises

The field effect describes a region of epithelium with preneoplastic changes from which a tumour might arise; but how is the field effect induced? Alcolea and colleagues used lineage tracing to track oesophageal epithelial progenitor cells in which Notch signalling is abrogated. They found that mutant clones do not undergo differentiation and so they are not naturally lost from the epithelium. Instead, the mutant clones promote the differentiation of neighbouring wild-type cells, leading to expansion of the mutant clones.