In particular, Zhang et al. explored the role of UPR signaling, identifying a relatively distinct set of UPR-related genes, including CEBPG, HYOU1, IMP3, KDELR3, MTHFD2, PDIA6, POP4, PREB, SRPRB, TATDN2, YIF1A, and ZBTB17, which were associated with survival outcomes and response to chemotherapy and immunotherapy in bladder cancer (Zhang F. et al., 2021). Here, POP4 is linked to urinary bladder cancer.