We observed that staining was negative in tumours, but positive in the adjacent normal epithelium, from both Cre-induced VillinCreERApcfl/+ and VillinCreERApcfl/+Bcl9fl/flBcl9lfl/fl mice (Supplementary Figure 7b), suggesting that in both cases, the second copy of Apc is lost via LOH. This evidence concerns the gene APC and neoplasm.