P4HB and metastatic neoplasm: PDI family proteins, such as AGR2, PDI, PDIA3, PDIA4, and PDIA6 are reportedly upregulated in cancers [10–16], which are correlated with cancer progression and metastatic disease in pancreatic [17], kidney renal clear cell carcinoma (KIRC) [11], ovarian cancers [18], glioblastoma [19–21] and lung adenocarcinoma [22].