To demonstrate that YAP nuclear accumulation is induced in WT epithelial cells neighbouring mutant tumour cells, we induced mosaic Apc loss in both VillinCreERT2;Apcflox/+ and VillinCreERT2;Apcflox/flox mice, allowing us to study non-recombined WT epithelial cells adjacent to or within Apc mutant tumours. This evidence concerns the gene YAP1 and neoplasm.