The HDM-allergic AD model was also established in Par2-/- mice, and found that HDM-Par2-/- mice displayed milder erythema, swelling and eruption, less hyperkeratosis and lymphocyte infiltration, and a decrease number of scratch bouts compared to HDM-WT mice (Figures 1B–E). This evidence concerns the gene F2RL1 and Hyperkeratosis.