TLR4 and asthma: While CCL-20 plays an important role in DC recruitment in allergy and asthma (82), PCS could bind in the interdomain pocket of epidermal growth factor receptor (EGFR) (83) and block signal transduction of toll-like receptor 4 (TLR-4) to inhibit CCL-20 production by airway epithelial cells and reduce allergic airway responses (81).