Examples include SKP1A (p19, S phase kinase-associated protein 1A), a component of the largest class of E3 ubiquitin ligases, SCF (Skp1, Cullin 1, a substrate recognizing F-box protein and Rbx1)[17,18], HSPA8 (heat shock 70-kDa protein 8, encoding chaperone Hsc-70)[19], and 19 S proteasomal protein PSMC4/S6b/TBP7, whose levels were decreased in PD. This evidence concerns the gene PSMC4 and Parkinson disease.