Therefore, many UCHs, including UCHL1, UCHL3 and UCHL5, have been found to be associated with the occurrence and development of malignant tumors via regulating the ubiquitin of target genes: oncogene Akt2 and hypoxia inducible factor 1α (HIF-1α) could be maintained by UCHL1-mediated deubiquitination and then promote growth of cancer cells [29–31]. Here, UCHL5 is linked to cancer.