SPI1 and neoplasm: In addition, USP22 was also reported to regulate tumor immunity and impact the antitumor immune response.[56] USP22 physically interacts with the C‐terminus of the PD‐L1 protein and CSN5, a known DUB of PD‐L1, therefore deubiquitinates and stabilizes PD‐L1.[33, 34] In addition, USP22 can also deubiquitinate and stabilize the SPI1 protein, thereby enhancing PD‐L1 transcription and expression.[47] In addition, USP22 regulates other targets impacting tumor immunity.