UCHL1 and Parkinson disease: UCHL1 (also known as PGP 9.5) is the most studied member of the UCH-class of cysteine protease DUBs and is associated with multiple types of cancers including lung (Hibi et al. 1998), colorectal (Yamazaki et al. 2002), pancreatic (Leiblich et al. 2007), and breast (Xiang et al. 2012) cancers as well as neurodegenerative diseases such as Parkinson's (Leroy et al. 1998) and Alzheimer's (Xue & Jia 2006) (Fig. 3).