For example, survival of differentiated rat PC-12 pheochromocytoma cells in culture is dependent upon the presence of nerve growth factor (NGF) and removal of NGF from the medium causes an increase in the activities of p38 MAPK and JNK which is necessary and sufficient to induce apoptosis [21]. The gene discussed is NGF; the disease is hereditary pheochromocytoma-paraganglioma.