DRD2 and schizophrenia: Studies of D2R interacting proteins, using yeast two-hybrid, co-immunoprecipitation, glutathione S-transferase (GST) pull-down and in vitro binding assays, have identified about 20 proteins with many of them relevant to schizophrenia (Wang et al., 2008; Shioda et al., 2010; Kabbani et al., 2012).