SIRT2 and Parkinson disease: Additionally, SIRT2 mRNA and protein levels were also unchanged in two cellular models of PD, i.e., MPP+ (1-methyl-4-phenylpyridinium)-treated primary culture neurons (Fig. 2i–l) and SH-SY5Y cells stably transfected with α-synuclein-A30P*A53T (Fig. 2m–p).