USP8 and ACTH-producing pituitary gland adenoma: Gain-of-function mutations of USP8 have been found in microadenomas of patients with Cushing’s disease, a rare disease where the secretion of large amounts of adrenocorticotrophic hormone by pituitary corticotroph adenomas results in an excess of glucocorticoids and hypercortisolism, putatively due to defective EGFR sorting (Ma et al., 2015; Reincke et al., 2015).