PPP1R1B and Parkinson disease: Bateup and co-workers [36] showed that the deletion of DARPP-32 in indirect MSNs produces a robust increase in locomotor activity and a decrease in Hal-induced catalepsy, whereas DARPP-32 inactivation in direct MSNs can abolish dyskinetic behaviors in response to the Parkinson’s disease drug L-DOPA [36].