The P2Y2 receptor was the first of this family of receptors that can be fully activated by both ATP and UTP. P2Y2 receptors are present on all of the body"s mucosal surfaces, including the lungs, eyes, upper airways, mouth, vaginal tract and gastrointestinal tract. P2Y2 receptors have also been found on non-mucosal surfaces, such as the retinal pigment epithelium. Activation of P2Y2 has been shown to stimulate mucosal hydration and mucociliary clearance in the lungs and upper airways and induce secretion of therapeutically significant amounts of fluid and tear components to the ocular surface. Thus, P2Y2 receptors are therapeutic targets for treating serious disorders including cystic fibrosis, a fatal genetic disease, retinal detachment as well as dry eye disease.