DLK1 and hereditary pheochromocytoma-paraganglioma: Strikingly, almost all treatment refractory metastatic adrenal cancers, i.e., ACC and pheochromocytoma/paraganglioma (PCPG), expressed high levels of DLK1 (Fig. 1A), which we also observed among primary adrenal tumors in the TCGA PanCancer dataset11 (Fig. 1B).