This gene encodes a cAMP-regulated phosphoprotein. The encoded protein is enriched in the caudate nucleus and cerebellar cortex. A similar protein in mouse may be involved in regulating the effects of dopamine in the basal ganglia. Alternate splicing results in multiple transcript variants.ARPP21 (CAMP Regulated Phosphoprotein 21) is a Protein Coding gene. Diseases associated with ARPP21 include Suppurative Periapical Periodontitis. GO annotations related to this gene include nucleic acid binding and calmodulin binding. An important paralog of this gene is R3HDM1.