APEX1 and familial pancreatic carcinoma: Intriguingly, GFRα1 overexpression by GFRα1-encoded lentivirus restored GDNF-stimulated cell proliferation in APE-deficient pancreatic cancer cells (Figure 1e,f), indicating that APE1 promotes GDNF-dependent pancreatic cancer cell proliferation by regulating GFRα1 expression.