While the importance of IL-13 in gastric metaplasia seems to be mostly related to mucus hypersecretion [110,111], which is a specific feature of SPEM [87,112], IL-33-dependent induction of IL-13 is required to promote metaplasia following parietal cell loss and chief cell transdifferentiation into a mucus-producing cell type. The gene discussed is IL33; the disease is Gastric Metaplasia.