HDAC6 and Parkinson disease: Specifically, here we: (i) evaluated the distribution of HDAC6 and its phosphorylated form, phospho-HDAC6, in PD and atypical parkinsonisms, such as MSA and PSP; (ii) analyzed the colocalization of phospho-HDAC6 with α-synuclein and phospho-tau; and (iii) checked for the interaction between phospho-HDAC6/HDAC6 and α-synuclein in PD.