ACE and adrenal gland pheochromocytoma: On the other hand, the IC50 values of ACE have also been observed less than 1 mM in different cell lines such as human lung fibroblast IMR-90 [44], human placenta trophoblast HTR-8/SVneo [45] and rat adrenal gland pheochromocytoma PC-12 [13] cells.