FIGURE 1: The pathological stages and dysregulated molecular events in PDAC development. The PDAC development process is categorized into pre-cancerous lesion (pancreatic intraepithelial neoplasia, PanINs) and malignant PDAC according to the pathological grade. Simultaneously, aberrant genetic alterations occurre at different stages of PDAC development, including activating mutations of KRAS and inactivation mutations of tumor suppressors, like p16/CDKN2A, p53, and DPC4/SMAD4.