RBX1 and hepatocellular carcinoma: Ubiquitination, as another important post-translational modification of PD-L1, is necessary for protein degradation.142 CASP8 (Caspase8) promotes TNFAIP3 (TNF alpha induced protein 3) (A20) expression, leading to PD-L1 ubiquitination and degradation.143 In HCC cells, 2,5-dimethylcelecoxib promotes HBx (x protein of HBV)-induced PD-L1 ubiquitination via RBX1 (RING box protein-1), an E3 ubiquitin ligase.144 Besides, berberine (BBR) is a proven anti-inflammation drug that can enhance PD-L1 ubiquitination and promote its degradation by binding to CSN5 at Glu76 to inhibit its deubiquitination.