Despite differences in immunohistochemistry protocols and criteria defining periostin overexpression in the setting of the same primary antibody among studies (rabbit polyclonal antibody, Ab14041), this discrepancy may also arise from molecular genetic differences between bladder urothelial carcinoma and UTUC, as recent studies indicate [33, 34]. Here, POSTN is linked to renal pelvis/ureter urothelial carcinoma.