There was no significant difference in BrdU positivity of epithelial cells in IL-4Rα−/− versus WT mice in either non-neoplastic mucosa or in adenomas (Figure 3A and B) suggesting that differences in epithelial cell proliferation did not explain the differences observed in ACF formation (a biomarker of tumour initiation) or tumour growth. The gene discussed is IL4R; the disease is neoplasm.