MUC1 and pancreatic ductal adenocarcinoma: HLA: human leukocyte antigen, PDA: pancreatic ductal adenocarcinoma, WT1: Wilms’ tumor gene 1, GEM: gemcitabine, MUC1: mucin, DC: dendritic cells, IV: intravenously, ID: intradermally, MSL: median survival time, DTH: delayed-type hypersensitivity, CTLs: cytotoxic T-lymphocytes, ICC: intrahepatic cholangiocarcinoma, OS: overall survival, PFS: progression-free survival, RFS: relapse-free survival.