COPS5 and cancer: This likely represents one of the several working mechanisms of IL-2 in treating cancer.22 A rationally-designed peptide PD-LYSO, containing a PD-L1-binding sequence and a lysosomal-sorting signal sequence from HIP1R, can target PD-L1 for lysosomal degradation.32 Curcumin inhibits deubiquitination activity of CSN5 to destabilize PD-L1 and benefits anti-CTLA-4 therapy.35 As mentioned above, PD-L1 palmitoylation can suppress mono-ubiquitination and degradation to stabilize surface expression.