Allergic proteases of HDMs, Der p 1, and Der f 1 can induce allergy by disrupting tight junctions [25], activating protease-activated receptor (PAR)-1, inactivating PAR-2 [19,26], and degrading and inactivating lung surfactant proteins A (SP-A) and SP-D [27]. Here, F2RL1 is linked to allergic disease.