Hence, classical PDAC typically consists of (low grade) well-differentiated tumor tissues [53,54,62], which frequently express (>10%) mucin markers associated with pancreatic differentiation [35], together with the O-linked glycosylated MUC5AC and MUC1 mucins, but not MUC2 or MUC6 [10]. This evidence concerns the gene MUC5AC and neoplasm.