SOX9 and pancreatic ductal adenocarcinoma: By lineage tracing, their study also suggested that upon the expression of SOX9, pancreatic intraepithelial neoplasia (PanIN) lesions and subsequently pancreatic ductal adenocarcinoma arise from ductal metaplasia of the pancreatic acinar cells, a phenomenon known as acinar-to-ductal metaplasia [38].