Many MCs mediators (PGD2, leukotriene C4 LTC4, IL-6, IL-13, TNF-α, tryptase, and chymase) interact with the epithelium, leading, altogether, to mucus hypersecretion by hyperplastic submucosal glands and epithelial goblet cells, which is a known key feature, especially in severe asthma [35,94]. The gene discussed is TNF; the disease is asthma.