Human pancreatic islet tumor cells maintained in vitro

Summary Tumor cells from two human insulinomas were maintained in culture for more than 6 months. The cultured cells synthesized and secreted proinsulin and insulin; and responded to cyclic AMP (1 mM) and tolbutamide (1 mM) stimulation with increased insulin release. In culture, these cells did not respond to stimulation by high concentrations of glucose (300 mg%) or by glucagon (10 g/ml).