CBL and neoplasm: Another E3 ligase, c-Cbl, has been shown to interact with the cytoplasmic tail of PD1 and mediate ubiquitin-dependent PD1 degradation in the tumor microenvironment.99 Ubiquitination and deubiquitination also regulate the stability of PD1 ligand 1 (PD-L1) in tumor cells, which contributes to the regulation of T cell function and antitumor immunity.100,101