To investigate the expression pattern of IL-35 in pancreatic carcinoma, we performed immunohistochemistry (IHC) staining to detect EBI3 and P35 co-expression in tumour tissues and the adjacent normal pancreas tissues (pancreatic tissues 2–3 cm around the tumour border; Supplementary Fig. 1) of five histopathological subtypes of pancreatic carcinoma (PDAC, mucinous carcinoma, giant cell carcinoma, malignant neuroendocrine carcinoma and acinic cell carcinoma). Here, EBI3 is linked to mucinous adenocarcinoma.