In vitro studies indicate that UDP amplifies cytokine production by epithelium,17 endothelium,18 and macrophages.19 In contrast, other studies demonstrate anti-inflammatory effects in asthma of P2Y6R or its primary agonist uridine, indicating that these receptors protect the lung against allergen-induced pulmonary inflammation by inhibiting the activation of effector T-cells.8,9 A possible source of the disagreement between these various studies is a lack of sufficiently selective purinergic receptor agonists and antagonists. The gene discussed is P2RY2; the disease is asthma.