LRRK2 and Parkinson disease: These effects may be functionally important in PD, because silencing ArfGAP1 expression in primary cortical neurons rescued the neurite shortening phenotype caused by overexpression of a disease-associated mutant LRRK2, whereas co-expression of ArfGAP1 and LRRK2 synergistically promoted neurite shortening (Stafa et al., 2012).