ATP6AP2 and pancreatic insulinoma: These findings, together with in vitro data that the suppression of Atp6ap2 gene expression induces apoptosis in INS-1 insulinoma cells (Figs. 4 and 5), suggest that the Atp6ap2 gene may be a possible therapeutic target for insulinoma and early stage NETs, but not for advanced NETs with higher proliferation activity.