SIRT2 and Parkinson disease: As we showed that GSK3β regulates the phosphorylation of SIRT2 and that the protective effect of blocking GSK3β in the PD cell model occurs through decreased SIRT2 phosphorylation, we next transfected SH-SY5Y cells with the GFP, GFP-SIRT2, GFP-SIRT2SA, or GFP-SIRT2SD plasmids for 24 h or 48 h.