USP4 and melanoma: For instance, USP4 is known to be overexpressed in melanoma cells, and its knockdown has been shown to mitigate the migration of melanoma cells in vitro.[36] USP7 is also overexpressed in melanoma and is negatively associated with the prognosis of melanoma patients.[37] Pharmacological inhibition of USP7 inhibits melanoma growth and progression.[37] However, the roles of other USPs in melanoma, along with the underlying mechanisms and their substrate proteins, remain elusive.