CDC42 and Parkinson disease: To substantiate the role of Cdc42 in D2R‐positive neurons in the spine structure and behavioral characteristics of PD, we generated conditional Cdc42 knockout (Drd2‐Cdc42KO) mice, by co‐injection of Drd2‐Cre and LV‐EGFP into the CPu of Cdc42loxp/loxp mice (Figure 6a).