To investigate the role of heat-shock protein Hsp90 in adrenocorticotropic hormone (ACTH)-secreting cells, and to explore the potential clinical application of an inhibitor of Hsp90, 17-N-allylamino-17-demethoxygeldanamycin(17-AAG) in corticotropinomas [also known as “Cushing’s disease” (CD)]. The gene discussed is HSP90AB1; the disease is ACTH-producing pituitary gland adenoma.