GSK3B and Parkinson disease: Furthermore, in vitro, Drosophila, mouse, and human data collectively suggest that GSK3β specifically phosphorylates Ser129 of α-synuclein (Figure 2A1), a post-translational modification predominant in Lewy bodies and in the PD brain that may enhance α-synuclein aggregation and/or neurotoxicity (Fujiwara et al., 2002; Chen and Feany, 2005; Anderson et al., 2006; Credle et al., 2015).