Hua et al. demonstrated that adenosine A3 receptor-deficient mice and mast cell-deficient mice are resistant to adenosine-induced airway hyperresponsiveness and that the reconstitution of mast cell-deficient mice with wild-type mast cells restored adenosine-induced airway hyperresponsiveness, whereas reconstitution with adenosine A3 receptor-deficient mast cells failed to restore it [31]. This evidence concerns the gene ADORA3 and airway hyperresponsiveness.