CXCR4 and pancreatic ductal adenocarcinoma: During the progression of pancreatic intraepithelial neoplasia (PanIN) (the accepted precursor lesions to pancreatic duct cancer) in mice and humans, CXCL12-CXCR4 promoted precancerous lesions of pancreatic duct cancer by increasing the frequency and intensity of its expression, partially dependent on MAPK signaling.