GDNF and pancreatic neoplasm: To determine which pathway is involved in APE1-mediated pancreatic cancer cell proliferation, MIA PaCa-2 cells were serum starved for 24 h and incubated with a MAPK/ERK kinase inhibitor (PD98059) or a PI3K inhibitor (Wortmannin) for 30 min prior to treatment with GDNF.