Emerging evidence have reported that USP18 predominantly plays a role in removing interferon‐stimulated gene 15 (ISG15), regarded as a ubiquitin‐like protein (Ubl), from substrate proteins.[25, 26] We first explored whether the protein stability of PD‐L1 was regulated by lncRNA BCCE4 using a cycloheximide (CHX) chase assay and observed that endogenous PD‐L1 was unstable and degraded rapidly in bladder cancer cells transfected with si‐BCCE4 (Figure S29A, Supporting Information). This evidence concerns the gene ISG15 and urinary bladder cancer.