Thus, the mucus layer in IBD is not only thinner, but also altered in function and mucin protein misfolding contributes further to spontaneous inflammation caused by ER stress (Pullan et al., 1994; Heazlewood et al., 2008; Strugala et al., 2008; Braun et al., 2009; van der Post et al., 2019; Kramer et al., 2023). The gene discussed is MUC5AC; the disease is inflammatory bowel disease.