POMC and neoplasm: More specially, USP8 mutation or EGFR ligand activation in ACTH PitNETs are associated with decreased tumor diameter and ACTH secretion, as previously reported.16 By contrast, EGFR T693 phosphorylation in silent TPIT activates the PI3K-AKT-mTOR pathway and results in invasive tumors without hormone hypersecretion.