We previously speculated that IL-13Rα2-mediated signalling by IL-13 might account for increased AOM-induced tumour initiation in IL-4Rα−/− mice based on increased colorectal mucosal expression of transforming growth factor β, upregulation of which is recognized to occur downstream of IL-13–IL-13Rα2 activation (17). The gene discussed is IL13; the disease is neoplasm.