POMC and adenoma: Over- or under-expression of many genes involved in EGFR recycling, cell cycle regulation (e.g., p27 and CABLES1), POMC expression and ACTH secretion (e.g., CREB), glucocorticoid receptor activity (e.g., HSP90), and more general granule sorting and exocytosis have also been found in USP8-mutated corticotrope adenomas, primary cultures, and in the murine corticotrope adenoma AtT-20 cell line [15,25].