MS4A2 and food allergy: The classic trigger for mast cell degranulation in food allergies is through IgE bound to high-affinity IgE receptors, FcεRI [36], but HIN1-induced mast cell degranulation is independent of IgE–FcεRI signaling [48], which further implies that melatonin targets IgE–FcεRI signaling on mast cell in food-allergic mice.