The DRD2 Dopamine Receptor is involved in the neuromodulation of appetitive behaviors. DRD2 may be linked to alcoholism and other substance-use disorders. Mutations in DRD2 in mice lead to the suppression of reward behavior with morphine and to the reduction of spontaneous movements, a phenotype resembling Parkinson's disease. Three alternatively spliced isoforms have been identified. DRD2 has been reported to be expressed in various regions of the brain, as well as in aorta, artery, eye, and spinal cord. ESTs have been isolated from normal pituitary and in brain, colon, lung, pancreas, and skeletal muscle cancer libraries.