On the other hand, several ubiquitin-specific peptidases, including USP7, USP22, OTUB1, and CSN5, regulate PD-L1 protein expression in an opposing fashion through removal of the polyubiquitin modification from PD-L1 and consequently protect PD-L1 from proteasomal degradation in cancer cells (20–23). Here, USP22 is linked to cancer.