An orally bioavailable quinazoline with potential antineoplastic activity. CP-724,714 selectively binds to the intracellular domain of HER2, reversibly inhibiting its tyrosine kinase activity and resulting in suppression of tumor cell growth. HER2, a member of the epidermal growth factor receptor (EGFR) family, is overexpressed in many adenocarcinomas, particularly breast cancers. OR A test used to help diagnose a type of pancreatic tumor called an insulinoma. After fasting, the patient receives an injection of insulin and the level of C-peptide (a substance released with insulin by the pancreas) in the blood is measured. In patients who have an insulinoma, the level of C-peptide is higher than normal.