Rat islet cell tumour. Established from a transplantable pancreatic tumour of the islets of Langerhans. The tumour originated in an irradiated NEDH inhibited albino rat and was maintained by serial transplantation in Nedh rats. After transplantation into athymic nude mice the cell line RIN-m was established from the fourth nude mouse heterotransplant, 9 days after the tumour was removed cells were exposed to cystine-free medium resulting in the complete elimination of fibroblast-like cells. RIN-m cells secrete insulin and somatostatin. High levels of L-dopa-decarboxylase and membrane bound secretory granules were detected.