USP18 and carcinoma: And USP18 also has the ability to affect cellular pathways (and expression of surface proteins), as demonstrated by its ability to (1) regulate the expression of the EGF receptor in carcinoma cells [37, 38], (2) inhibit tumor necrosis factor- (TNF-) related apoptosis-inducing ligand- (TRAIL-) induced apoptosis [39], and (3) employ USP20 to promote deubiquitination of the mitochondrial adaptor protein STING [40].