HIF1A and adrenal gland pheochromocytoma: HSP90 is involved in the stability of HIF1α.9 HSP90 has been shown to be overexpressed in metastatic PGL/PCC compared with benign PGL/PCC.82 Inhibition of HSP90 leads to downregulation of HIF1α and is a potential target for therapy in metastatic PGL/PCC.83