Hydrolase that deubiquitinates target proteins such as the receptor ADORA2A, PDPK1 and TRIM21. Deubiquitination of ADORA2A increases the amount of functional receptor at the cell surface. Plays a role in the regulation of quality control in the ER. Interacts with RB1 (both dephosphorylated and hypophosphorylated forms). Interacts with ADORA2A (via cytoplasmic C-terminus); the interaction is direct. Interacts with RB1, RBL1 and RBL2. Overexpressed in small cell tumors and adenocarcinomas of the lung compared to wild-type lung. Expressed in the hippocampal neurons. Belongs to the peptidase C19 family. USP4 subfamily. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.