P4HB and urinary bladder carcinoma: Wang once reported that targeted inhibition of P4HB promoted cell sensitivity to gemcitabine and induced cell apoptosis via PERK/eIF2α/ATF4/CHOP signaling in urothelial carcinoma of the bladder (Wang et al., 2020), and Zhang discovered that OTUB1 facilitated bladder cancer progression by stabilizing ATF6 in response to endoplasmic reticulum stress (Zhang et al., 2021c).