The pancreatic expression of SDF-1/CXCL12 and its receptor CXCR4 was also studied in a subset of IgG4-RD patients with autoimmune pancreatitis (IgG4-RD AIP) and compared to what was observed in the pancreatic ductal adenocarcinoma (PDAC). The gene discussed is CXCL12; the disease is pancreatic ductal adenocarcinoma.