P4HB and benign prostatic hyperplasia: AGR2 is a member of the protein disulfide isomerase (PDI) family, which was reported to regulate protein homeostasis regulation and maintain epithelial phenotype, indicating an undeniable role in cancer progression.32,33 Immunoblotting analysis (Supplementary Fig. 5b) validated that the abundance of AGR2 were remarkably downregulated in tumor- versus BPH-derived primary cell lysates and membrane proteins (Fig. 4b, d) and were significantly related to the clinical malignancy of patients (Supplementary Fig. 5c).