IGF2 and hereditary pheochromocytoma-paraganglioma: We observed a 20-fold higher expression level of INS-IGF2 transcript in tumor tissues of relapse patients when compared to complete remission patients, in contrast with a modest twofold higher expression level of IGF2. The overexpression of INS-IGF2 has been reported in cancers such as pheochromocytomas [51] and was shown to promote cellular proliferation and migration in lung cancer [52].