P4HB and neoplasm: In our previous proteomic study, 6 proteins (ERO1Lβ, TRAM1, GRP94, BIP, P4HB, PDIA4) (Table 2) involved in the ER protein processing pathway were found to be downregulated in SPTP tissues compared to the normal pancreas tissues, whereas these proteins were mainly localized to the cytoplasmic fraction of the normal pancreas and tumor tissues.