PITUITARY: Menin is a Smad3-interacting protein; inactivation of menin blocks transforming growth factor (TGF)-beta and activin signaling, antagonizing their growth-inhibitory properties in anterior pituitary cells.
LOH of chromosome 11 was also detected in the prolactinoma of this patient, which indicates that the MEN1 gene has a tumor suppressor effect in the pituitary.