First we compared the effects of Pygo2 loss during the acute phase of intestinal tumor initiation induced by homozygous truncated Apc (Apc LOF; Pygo2+/+, +/− and −/−) and by heterozygous stabilized ß-catenin (Ctnnb1 GOF; Pygo2+/+, +/− and −/− ; Figures 2, 3). This evidence concerns the gene CTNNB1 and intestinal neoplasm.