HDAC9 and Parkinson disease: Other studies demonstrated the protective effect of pan-HDAC inhibitors such as valproic acid, sodium butyrate, phenylbutyrate, suberoylanilide hydroxamic acid and trichostatin A in in vitro and in vivo models of PD acting through different mechanism listed in Table 4 (Gardian et al., 2004; Chen et al., 2007, 2012; Wu and Guo, 2008; Kidd and Schneider, 2010, 2011; Zhou et al., 2011, 2014; Rane et al., 2012; St Laurent et al., 2013; Harrison et al., 2015; Suo et al., 2015; Sharma et al., 2015a; Kim et al., 2019; Getachew et al., 2020; Hsu et al., 2020).