POMC and neoplasm: Moreover, in order to determine if BET inhibitors may also represent an effective novel therapy for corticotrophinomas in reducing proliferation and increasing apoptosis of these pituitary cells, we first investigated the mouse corticotroph tumour cell line AtT20 for expression of the BET protein family members and then the effects of the BET inhibitors JQ1 and PFI-1 on proliferation, apoptosis and ACTH secretion by these pituitary cells.