G6PD and hereditary pheochromocytoma-paraganglioma: Chettimada et al. (32) showed that G6PD expression was increased by hypoxia in pulmonary artery smooth muscle cells, while Gao et al. (33) showed that hypoxia caused an increase in G6PD expression in PC12 rat pheochromocytoma cells, a classic O2-sensitive excitable cell, but not in nonexcitable Buffalo rat liver cells.