Spinophilin is a regulatory subunit of protein phosphatase-1 catalytic subunit (PP1; see MIM 176875) and is highly enriched in dendritic spines, specialized protrusions from dendritic shafts that receive most of the excitatory input in the central nervous system (Allen et al., 1997 [PubMed 9275233]).[supplied by OMIM, Mar 2008]