USP21 and non-small cell lung carcinoma: Additionally, Yang et al. uncovered the potential role of USP21 in immune escape due to the mechanism of USP21-mediated PD-L1 stabilization, and suggested the positive correlation between USP21 and PD-L1 in lung cancer, especially in lung squamous cell carcinoma, a main subtype of NSCLC (Yang et al., 2021).