Mutations in LRRK2 (leucine-rich repeat kinase 2) are a relatively common cause of inherited PD (Parkinson's disease), but the mechanism(s) by which mutations lead to disease are poorly understood. In the present paper, I discuss what is known about LRRK2 in cellular models, focusing specifically on assays that have been used to tease apart the effects of LRRK2 mutations on cellular phenotypes. LRRK2 expression has been suggested to cause loss of neuronal viability, although because it also has a strong effect on the length of neurites on these cells, whether this is true toxicity or not is unclear. Also, LRRK2 mutants can promote the redistribution of LRRK2 from diffuse cytosolic staining to more discrete structures, at least at high expression levels achieved in transfection experiments. The relevance of these phenotypes for PD is not yet clear, and a great deal of work is needed to understand them in more depth.