MUC5AC and neoplasm: Our results demonstrated that these S100P + SPP1− iCCAs were more like iCCAphl (all were positive for MUC5AC and mucin production), while S100P-SPP1 + iCCAs were more like iCCApps (mostly were negative for MUC5AC and mucin production) by performing the staining of Alcian blue staining (to detect the mucus secreted by mucous tumor cells), immunohistochemical staining of MUC5AC (essential for mucus production), and HE staining (morphology) in these samples (Supplementary Fig. 4).