Second, while mean ACTH concentrations were significantly higher among patients with macroadenomas, there was a significant overlap of ACTH values between the groups, suggesting that large tumors may produce a similar amount of ACTH as small tumors; thus, these findings may be partly due to low level of hormone production per tumor mass or due to disturbances in the regulated exocytotic pathway [25]. The gene discussed is POMC; the disease is neoplasm.