CDKN2A and hereditary pheochromocytoma-paraganglioma: The human pheochromocytoma cell line hPheo1 is the first and only human hTERT-immortalized pheochromocytoma cell line with a normal diploid chromosomal set except for a small deletion of the 9p region, encompassing the CDKN2A gene encoding the p16 and p14ARF proteins.