TR4 is overexpressed in corticotroph adenomas and corticotroph tumor cell lines and activatesPOMC by binding to its promoter, an effect that is enhanced by phosphorylation of TR4 through the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. The gene discussed is NR2C2; the disease is ACTH-producing pituitary gland adenoma.