Both cell lines originated from sporadic pheochromocytomas and, in contrast to the studies described above, both were clearly derived from genuine chromaffin cells, showing a close morphological resemblance to PC12 cells, production of catecholamines or the expression of markers including chromogranin A, human neurofilament protein, S100 and NSE. The gene discussed is ENO2; the disease is hereditary pheochromocytoma-paraganglioma.