MUC1 and mucinous adenocarcinoma: However, Onoe et al. [14] revealed that most IPNB with ≤50% invasive component showed MUC1+/MUC2− carcinogenetic pathway progressing to papillary/tubular adenocarcinoma, whereas a few IPNBs with ≤50% invasive progressed to mucinous carcinoma characterized by a MUC1+/MUC2+ pathway.