RHOA and Parkinson disease: In the presence of an increased intracellular Calcium influx, the calcium-calmodulin axis activates and starts a phosphorylation cascade that leads to activation of RhoA and its effector ROCK that in turn activates the LIM Domain Kinase 1 (LIMK1), a Cofilin inhibitor; when Cofilin activity is impaired, neurons undergo Actin dynamic deregulation and loss of cytoskeletal architecture, which may contribute to axonal degeneration and loss of dopaminergic neurons in PD (Figure 6b) [286].