PTGDR2 and allergic rhinitis: Owing to its high selectivity over all other tested receptors and enzymes, and the fact that its chemical structure is closely related to ramatroban which has proven efficacious in various animal and human studies of allergic rhinitis and asthma [44-50], TM30089 emerges a suitable research tool to explore the contribution of CRTH2-signaling in allergic airway inflammation in vivo.