In humans, PAR-2 expression is increased on airway epithelial cells [5] and smooth muscle cells [6] of patients with asthma, while PAR-2 expression on peripheral blood monocyte subsets correlates with asthma severity [7]. PAR-2 is encoded by the coagulation factor II receptor-like 1(F2RL1) gene on chromosome 5 [8]. Here, F2RL1 is linked to asthma.