We confirmed this for goblet cells, using Period-Acid Schiff (PAS) diastase (PAS-D) staining33: we found about twice as many PAS-D-positive cells in Bcl9/B9l DKO vs control adenomas (Fig. 4f–h), although the adenomatous PAS-D signals (labelling intracellular mucus) were smaller than those from normal goblet cells (Fig. 4f, g; high-magnification views), suggesting that these metaplastic goblet cells are not fully differentiated. This evidence concerns the gene BCL9 and adenoma.