APC and neoplasm: Since Apc mutant intestinal tumours present differentiated tumour cells, we evaluated if Notch1 is expressed in such cells by immunostaining for differentiation markers for secretory cells, such as Agglutinin (Ulex Europaeus Agglutinin, labelling both Paneth and Goblet cells), Lysozyme116 (a specific marker of Paneth cells) and Mucin217 (expressed in Goblet cells) (Fig. 1d).